by Brian Tomasik
First written: 5 Aug. 2014; last update: 14 Feb. 2017


This page describes my experiences with romance, what I would find attractive in a partner, the wonders of love, the downsides of love, why I like being single, and how romantic love relates to altruistic love.

My history with romance

Ages 0-25

Growing up, I had little interest in romance. I remember thinking that girls in my class were pretty even as early as first grade, but I didn't understand why someone would want a relationship.

This continued into teenage years. While some of my classmates began dating, I didn't think about the topic except through TV shows and occasional conversations with friends. During high school, I spent almost all my waking hours on homework, so romance would have been a non-starter anyway.

The trend continued into college. While I was somewhat less busy than in high school, I continued to focus on academics and learning about reducing suffering in the world. I had a few small crushes, but I never took things further because I was focused on what I considered more important work.

At age 23, a year after graduating from college, I created a profile on OkCupid because I thought I might benefit from the companionship of a relationship. Post-college years are more solitary than college years, which explains some of the difference in my dispositions. I looked around the site and messaged a few people, but no one replied, and I didn't find any of the people to be particularly good matches. After several weeks, I mostly gave up, though I kept my profile open.

Age 25

Around age 25 I began to understand better the feelings that would motivate a relationship. I revisited OkCupid and found some interesting people there, though all the conversations trailed off after a while. I mostly retired from OkCupid once more.

Shortly thereafter, I met someone online but not through a dating site. Soon this turned into an intense long-distance romantic relationship. It lasted about 4.5 months, at which point my girlfriend decided to break up. I was sadder than I had ever been, but I tried to remind myself what a friend told me: If you really love someone, you want her to be happy. I felt glad that the wonderful memories would remain and that our moments together persisted eternally in the spacetime of our block universe.

Ages 26 onwards

After the breakup, I returned to OkCupid for a long time. Both there and on Facebook, I found a number of possible leads for future relationships, but one way or another each of those possibilities eventually closed out. By the end of age 26, I decided I was okay with this; I didn't feel like a relationship would necessarily improve my happiness by that point.

This is basically where I remain to this day, though I maintain many fond feelings about romance, as I'll discuss later in this piece.

Factors relevant to attraction

I think it's helpful to talk often with a romantic partner about why you're attracted to him/her. In addition to being informative, this can serve as a positive-psychology exercise in which you focus on what you have instead of what you don't. Your partner can feel elated from the praise, and you can feel warm giving it.

Following are some features that I think are important for my sense of attraction.


Sadly, I can't feel romantic sparks for other men. My brain seems to do some internal computation that prevents such sparks from forming. I have some very close male friends to whom I would plausibly feel romantic attraction if they were female.


I find altruism really important to romantic attraction. I've imagined relationships with people who don't care very much about helping others, and even if such people are really smart, I have a hard time feeling sparks. I have a sense of "Meh, why should I be excited about this relationship?"

One reason altruism is great is that it could enable collaboration on important topics. But beyond that, there's something viscerally compelling about a woman who wants to reduce suffering, especially suffering by animals or digital agents, which are often neglected in mainstream discourse. Most of my crushes have been on women who were passionate about altruism, especially altruism for animals.

Along with altruism typically come traits like frugality with money, so that more savings can be donated. Not conforming to social expectations like expensive gifts is part of that.


When I was younger, I told myself that physical attractiveness doesn't matter. Caring about it is just "shallow" and "superficial". Unfortunately, I've come to realize this isn't the case. The brain's neural network for romantic sparks seems to include a "physical beauty" sub-network that can't be turned off even by effort of the will. I wish this weren't true, but life really is not fair.

Helen Fisher distinguishes lust, romantic attraction, and attachment as separate brain systems. Obviously pulchritude is relevant for lust, but I find that it also plays a role in romantic attraction.

Despite the "ugly fact" that beauty matters, society takes beauty too far. Our beauty obsession causes some women to waste inordinate amounts of time on makeup, shaving, grooming, clothing selection, and similar activities. It may encourage dieting and eating disorders. The money used on a cosmetic-surgery operation could have helped hundreds or thousands of suffering animals. Yet the "beauty" rat race still leaves 80 percent of women feeling insecure with their body images. And to the extent that beauty is a positional good, no net benefit accrues as a result of this.

I don't mean to imply that beauty obsession is purely cultural. It's a classic prediction of evolutionary psychology that men should care a lot about beauty as an indicator of youth and fertility. We can even put a positive spin on male "shallowness" by saying that it's designed to make sure the babies produced are healthy. Of course, in the modern age, cosmetics aim to override the underlying signal that beauty carries about a woman's good genes and healthy development.

Even though there are natural reasons for beauty to matter quite a bit, biology is not destiny, and we can make progress toward reducing cultural emphasis on beauty. One documentary about faces that I watched noted that part of the problem is we see too many beautiful people -- far more than if we lived in a local tribe. Marketers are engaged in an arms race to use the most attractive models to sell their products, as a result of which expectations are set too high. I think ads that use attractive people are somewhat evil, and the world would be better off without them. We wouldn't allow advertisers to employ small doses of addictive drugs to sell products; why is it ok when the addiction-inducing substances are visual rather than chemical? And of course, the impact on perceptions of body image are not healthy.

Some countries have taken steps in this direction, such as with Spain's body-image law, Israel's law against too-thin models, and a proposal for a Self-Esteem Act in the US to label photoshopped images. These are small first efforts, but I might prefer something stronger. On the other hand, there unfortunately may always be some amount of selection in promotional images for those who are more attractive, because each marketer doesn't want to be outcompeted by the others who are using such images.

Intelligence and success

A friend of mine introduced me to the word sapiosexual. I think intelligence is attractive on a visceral level beyond conscious "on paper" kinds of compatibility assessment. A similar statement applies to someone who is really good at what she does.

Kindness and positivity

I once heard advice for business managers that there's no such thing as too much praise as long as it's warranted. I feel the same way about positive emotions in general. There's no such thing as being too sweet or too happy, as long as those expressions are sincere. Being around cheerful people just makes me feel good, because their emotions are contagious. I also connect well with people who are very empathetic, compassionate, and caring. That said, it's also important to recognize time constraints and not spend excessive effort checking in with one's partner.

On-paper attributes

A relationship has to be practical, so my interest is often curtailed when things wouldn't work from a practical standpoint. For example, in a relationship I would need to

  • remain childfree
  • not spend more than 30-60 minutes per day in the long run on the relationship
  • stay inside most of the time and not travel much.

It would also be important for the person to be okay with my treadmill desk, STI testing, indefinite separate finances, my unconventional viewpoints, and complete honesty.

Being loved back

Being loved by another person is a strong component of my feeling reciprocal love for her.

Being in love

Relationship behaviors

My first relationship came very "naturally", as Selena Gomez would say. I acted just like my normal self and appreciated the fact that I could be totally comfortable with that. I find dating advice about "playing the game" to be distasteful, even though it's certainly possible that modest steps in that direction could improve one's general desirability -- in a similar way as your odds of getting a job at a bank improve if you wear a suit to the interview.

Personally, though, I don't really care. "F*** dat sh**", I said. I suspect that on average, the women I would get along with best are less inclined to care about conventional alpha-male signals, though as is the case with pulchritude, there may be some extent to which the attractiveness of such features is deep-seated and inaccessible to conscious modification, even by otherwise really compatible people.

One thing I found striking about my relationship was how well my favorite Mister Rogers songs applied to it. "It's You I Like" is just as wonderful when seen as a romance poem as when used as a parent-to-child melody. In general psychologists observe how people in love act like children. That said, Mister Rogers is decidedly not just for children. We adults have at least as much to learn from many of his lessons.

Being in love also brought out creativity and humor. I was more likely to think of dumb jokes, share nice pictures, and compose thoughtful emails about my emotions. At one point I wrote a gratuitous short story. Evolutionary psychologists speculate that sexual selection may have played a role in developments like humor, language and music, and other displays of ability. Whether or not this is true, the enhanced creativity that comes with being in a relationship doesn't feel like an attempt at signaling, but then again, neither does crying feel like an attempt at garnering sympathy or maternal love feel like an attempt to pass along genes.

The wonderful feeling of love

Being in love was unlike any other form of happiness I've experienced. It was a sort of omnipresent warm glow that filled everything in life. Of course, many other things are enjoyable and even deeply meaningful in a long-lasting, satisfying way, but love had a particular texture that made it clearly distinguishable. Sometimes I still have moments when I fall back into that feeling, perhaps when contemplating old memories, and the distinctive quale returns: "Ah, that's what love feels like. Wow."

Urban Dictionary has a nice entry on "true love". It's too long to quote in its entirety, but it includes these lines:

Love is the greatest gift God ever gave man. [...] Love is pure happiness. Love is the feeling you get when all you have to do is think of her and it brings a smile to your face and a yourning [sic] to your heart.

Bertrand Russell expressed the feeling perfectly in his autobiography:

in the union of love I have seen, in a mystic miniature, the prefiguring vision of the heaven that saints and poets have imagined. This is what I sought, and though it might seem too good for human life, this is what – at last – I have found.

Love is not like anything else in this world (that I have experienced, at least). It really seems to be from heaven.

After I fell in love, everything associated with my girlfriend seemed to have a magic glow. It was as though she was King Midas, with whatever she touched turning to gold. Even the bare letters of her name, written in an unadorned fashion, could trigger a significant emotional response. This makes sense in light of the associative-network structure of our brains.

It's not a surprise that so many pop songs, TV dramas, books, and other cultural artifacts center around romance. Song lyrics about love became more vivid after I experienced what they talk about for myself. I have a newfound appreciation for romance stories. I really like the happy ones; they trigger an "aww, that's sweet" feeling.

Love's critics

Sometimes love is said to be "overrated". I personally don't agree, but different strokes for different folks. Of course, it is true that love

  • is not the best way to make long-term decisions
  • can lead to impulsive behavior
  • may be fleeting

and so on, but none of this means it can't be an incredible experience -- definitely the best feeling I've had in my life.

Sometimes romantic love is claimed to be a special favoritism. To value one person requires that you value everyone else less. I don't think this has to be true. Subjectively, I may even love everyone more as a result of romantic love (see the final section for further discussion). Of course, our time and money are finite, so as a practical matter, we will end up spending more resources on someone we love. But our resources are not necessarily fixed, especially when it comes to intangible interpersonal variables like cheerfulness, friendliness, respect, and patience. Far from being limited, these traits may grow the more they're exercised.

Finally, critics may scorn the idea of a "soulmate" by pointing out that statistically, the world must contain many people who are at least as good as the person you think is your soulmate. There are too many people in the world and too few interactions for that not to be true. However, this ignores the path-dependent nature of romance. Love hormones rewire a lover's brain toward his or her loved one. After these changes happen, it may literally be the case that no one else in the world would elicit the same degree of love response as your loved one -- at least without significant further rewiring toward that other person. This is not mysterious. I would conjecture that a sufficiently complex image-classification neural network can be trained to fire more strongly for some particular image than for basically any other image.


Scientists debate whether and how much an "imprinting" process is involved in romance. It's clear that imprinting and reverse imprinting play important roles in sexual attraction. Some defend an imprinting hypothesis in the romance context, while others deny it. My own subjective experience jibes with some degree of imprinting.

I once heard someone say that her idea of the perfect boyfriend was shaped around her current boyfriend, rather than conforming to some independent standard. I heard another person say exactly the opposite: She has a fixed set of attributes for an ideal boyfriend by which she assesses potential boyfriends. I think I fall somewhere in between these two. Probably being in love shifts one more toward the first approach, because love tends to downplay negative aspects of one's beloved ("love is blind").

Love's dark sides

Even if I don't buy the criticisms discussed above, I agree that love does have some problems.

Addiction and rehabilitation

During my relationship, I craved interaction with my girlfriend, and if she was too busy to talk on some night, I would still think about her obsessively. ("A day without you is like a year without rain", says Selena Gomez.) I would write emails so as to continue engaging my romance brain circuits and pretend as though I was having a conversation. Knowing that she would read the emails made the process not vastly worse than talking with her directly. Still, the cravings were clearly similar to those of an addict, and addiction is not a pleasant experience. One feels out of control of one's emotions.

Over the months after the breakup, I remained quite sad on many days. Gradually the sad times became less frequent, though they could come roaring back at full intensity periodically. After the breakup I still felt a very strong need for romantic companionship. By about a year later, that feeling had waned, much like a drug addict's waning cravings for his drug following a period of rehabilitation.

This is not just an analogy. As Helen Fisher says, "romantic love is one of the most addictive substances on Earth." The brain's dopamine system evolved for (among other things) food, sex, and romance, and drugs of abuse are just hijacking that system.

I don't have experience with recreational drugs (and don't intend to, since it's unwise to start addictions), but I can imagine that some of them (empathogens??) may cause feelings similar to being in love. Perhaps there are regions of the brain that can be stimulated to induce the same. Yet drugs are regarded as shameful by society, while "falling in love" is often seen as one of the most important, rewarding, and special moments in life. Why the difference? Some reasons:

  • Falling in love "is productive" in that it helps society continue, by facilitating reproduction and two-parent households. Of course, one can debate whether reproduction is a good outcome, but those who survive in the long run will tend to think so, because those who disagree tend to die out. (That said, ritual celibacy remains surprisingly strong as a cultural ideal in the face of such pressures.)
  • Falling in love is more or less unavoidable, unless you live in Antarctica with only members of your own gender and no access to the outside world, or unless you manipulate your body's biochemistry. Society is less likely to "judge" things that everyone does (although traditional religions have been rather successful at doing so in many other areas of life!).
  • A "real" relationship may evoke many kinds of brain activation that drugs or brain stimulation would not. Maybe this is the reason people talk of "empty hedonism" with drugs: It represents stimulation of some pleasure regions without the full suite of somatic, cognitive, and belief-based brain changes that would accompany a "real" experience of something like being in love.

In my experience, love is very much a belief-based phenomenon. What matters is knowing that you and your partner love each other; this is more important than any specific sensory stimuli.

For this reason, I would be very happy with a long-distance relationship. Skype does a lot to break down distance barriers; indeed, Nick Bostrom's marriage is mostly long-distance over Skype. What I value most is emotional intimacy and the knowledge that you and your partner really care about each other in a romantic way. Oddly, it seems that maybe ~99% of people OkCupid don't feel the same, as judging by almost ubiquitous "near me" specifications in what people are looking for. (Even to the extent that I care about distance, it seems to me still a better strategy to look worldwide, because otherwise how are you going to find the really best matches? But I think many people are less picky about a partner's interests than I am, as a result of which they probably have many good local matches available.)

A friend of mine suggested that another reason for the difference in social attitudes towards drugs vs. romance is that most people, being naive dualists, haven't internalized the fact that romance too is just a biological phenomenon. This may be part of the story as well, but I don't think it's the whole story. Even if I had no altruistic obligations, I don't think I would "wirehead" to experience romance; I'd rather have a "real" romance experience, even if it felt less hedonically pleasurable. This is one of my stronger anti-experience machine intuitions. I have less intuition in this direction for other pleasures. Love seems somehow more "holy"; context and genuineness matter a lot.

Time sink

Love is also a spectacular time sink. During my relationship, I was able to feel bliss all by myself for an hour while going to the store just by thinking about my girlfriend. I didn't even think of getting bored, and I could have kept going. But this meant I wasn't listening to podcasts the way I usually would have done, and hence, I wasn't learning things that I could use to inform altruism work.

During the turbulence before the breakup, it was even worse. There were entire days when I felt "useless", as one of my friends called it -- i.e., I couldn't do much of anything other than mope around, cry, chat with my girlfriend, continue feeling anxious, and cry some more. It wasn't depression in the conventional sense, which I associate more with lack of feeling and listlessness. Rather, it was sort of an active, emotion-rich sadness, like pacing around one's prison cell for hours on end, wondering how things will turn out, and recounting old memories a million times in my head.

After the breakup, I continued to be sad for a long time. I actually didn't find the sadness unpleasant; it was a sort of "meaningful" sadness, similar to watching a tragic movie. I don't know that I would cut out these experiences from my life if I could. That said, they were amazingly unproductive from the standpoint of other projects. Rather than occupying my hours with blissful thoughts as before, I occupied them with the "sweet sorrow" of old memories, but the lack of ability to focus on other projects continued. If I were to put all the anxious and sorrowful moments alongside each other, they would have probably stretched over a few weeks -- all time during which I wasn't getting other things done.

Costs of kids and romance

Even when everything is going well, intense romantic love is a roller-coaster ride of emotions. Bliss is interspersed by cravings, and both may be accompanied by some sense of guilt about not being more productive in helping animals that are being tortured at that very moment. Of course, I think it's altruistically important to experience the array of life's emotions in order to develop a deeper appreciation of what life is about. If you don't, how will you know what matters and in what directions your altruism should push? But there are diminishing returns to any given experience, and romantic love demands a lot of attention.

I wrote an essay (during my relationship, actually) about the "The Cost of Kids". It points out just how much time investment is required for parenting, especially for good parenting. That said, some people feel that having children would be among life's most rewarding experiences, and they may be incapacitated by not having children (to greater or lesser degrees depending on the person).

Romantic relationships are similar. They require many minutes per day (or maybe hours, especially in the early phases). Like with raising a child, this time cost may not be optional, because if you're in love, it's not easy (and not healthy) to ignore your feelings and do something more productive. Of course, you can learn a lot from a relationship -- maybe more than from a crying baby because your partner can talk about a wider range of topics -- but there remain plenty of facets to emotional intimacy that are rather repetitive and uninformative.

Still, people may feel that romance cravings are too strong and that life would be less bearable without romantic love, so the cost is worth it. The Muppet Movie contains a brilliant song, "I Hope That Something Better Comes Along". Before they begin singing it, Kermit the Frog and Rowlf the Dog exchange these thoughts:

Rowlf: That's why I live alone.
Kermit: You do, huh?
Rowlf: (starts the song's intro) Yep. I finish work, go home, read a book, have a couple of beers, take myself for a walk and go to bed.
Kermit: Nice and simple.
Rowlf: Stay away from women. That's my motto.
Kermit: But I can't.
Rowlf: Neither can I. That's my trouble...

In addition, there may be cases where romance enhances productivity. One of my coworkers called it combining 1 and 1 to make 11. During my relationship, I felt emboldened to take on a project that I had previously resisted, because now I felt like I had an emotional safety net and could tolerate the occasional unpleasantness of the task in a way that I wouldn't have been able to do when I was single. In "I Hope That Something Better Comes Along", Rowlf the Dog calls this "a new leash on life." Moreover, if you and your partner share altruism interests, you can collaborate together to great effect. I think of this as "the best of both worlds" -- doing something to help others and spending time with your girlfriend simultaneously.

It's also worth noting that the cost of kids is not independent of the cost of romance. Even if you intend to remain childfree, what if your partner changes her mind? What if you've fallen so deeply in love that you don't feel you can leave the relationship? At that point you'd be between a rock (having the kid) and a hard place (breaking your heart by leaving). This is why I soon realized that if I searched on OkCupid, I absolutely had to use the "doesn't want kids" filter, and I also biased my evaluations toward older ages where women would be (slightly) more certain about their impulses regarding parenthood. Doing otherwise would be like playing with fire, because it could lead to a relationship where one of three things happened:

  1. my partner eventually would have to leave to find someone who would have kids
  2. I'd be persuaded to reverse my vasectomy
  3. we'd adopt a kid.

The childfree requirement also made dating outside of OkCupid quite difficult, because information on whether someone wants kids is not listed anywhere else, and it's not the kind of question you can ask someone until you know her pretty well. And then at that point, there's only a maybe ~10% chance she'll be certain she doesn't want kids, even adjusting for the observation that more educated women are more likely childfree.

Of course, there's some chance that your own feelings about kids may change too. As Kermit says in "I Hope That Something Better Comes Along":

I don't mean to scare ya, my friend, but I betcha
Come "Father's Day", the litter bug's gonna getcha;

In general, this impulse might be facilitated slightly by being in a relationship?

The joys of being single

You own your time

One aspect of a relationship that I find most unfortunate is needing to coordinate with the schedule of someone else. I'm bad at "timing" my emotions. If I want to be with my partner, I want to be with her now, and it's hard to wait until a scheduled appointment. Likewise, if I'm already feeling good, it seems a waste to get a "boost" from talking with my partner. The extra dopamine hit when I'm already in the mood to get work done feels (not just metaphorically but also somewhat literally) like eating (vegan) chocolate cake when you're already stuffed full.

Romance is good for rejuvenation -- a source of pleasure and a way to relieve stress. It would be best if it could be applied when it's needed most. That's possible with many other pleasures in life -- exercise, reading, entertainment -- but not when another human is involved. Being in a relationship is thus sort of like eating meals on a fixed schedule rather than when you're hungry. It means you sometimes eat when you're full and other times starve.


Ultimately what's good about being single is its tranquility. You've stepped off the emotional roller coaster, even if that roller coaster may have been the best experience of your existence. Life in general is better without addictions. Romance is the most wonderful addiction I've ever had ("You drive me crazy, but it feels alright", says Britney Spears), but I still may be better on the whole without it.

The Buddhists are right: Inner peace comes from removing sources of desire, rather than falling into a cycle of satisfaction followed by renewed craving. I've experienced this fact in many other areas, such as when I became addicted to my chewing gum but then was able to give it up. Life is easier if you don't have to manage your level of fulfillment or craving all the time.

Of course, maybe biology would do this naturally after a while. People say the dopamine rush of romantic love fades within 6-24 months, ushering in a more tranquil kind of relationship. During our relationship, I told my girlfriend I would probably look forward to this stage so that I could become more productive once again.

In any case, I'm doubtful whether I could fall in love again at this point. Since about a year after my relationship ended, my brain felt "damp" such that "sparks" had a harder time forming. When I did attempt a new relationship, the process had a bit of a "been there, done that" tenor to it, making it not as special as the first time. Subjectively it feels sort of like my brain was a firecracker that could only be exploded once. That said, taking the outside view, many people fall in love many times, and brains are good at resetting themselves. But I'm fine and probably even glad if I don't fall in love again. I've had my moment in the sun, and now I'm happy to enjoy working for suffering animals. Of course, it's plausible that this too shall pass, and a stronger romance drive will return.

Other sources of fulfillment

If I felt like I needed a relationship, I would still pursue one. Romance has a real time cost, but you gotta do what you gotta do if you're distracted by cravings. Fortunately, I generally feel completely satisfied being on my own.

The main reason is that I really enjoy what I do. I'm blessed to work on fascinating and meaningful problems. I'm in love with reading, writing, and learning. Russell noted this as his second passion:

I have sought knowledge. I have wished to understand the hearts of men. I have wished to know why the stars shine. And I have tried to apprehend the Pythagorean power by which number holds sway above the flux.

Another reason why I do well being single is that I have several wonderful close friends with whom I can share my daily news and inner feelings. In addition, Facebook conversations are a helpful source of social stimulation when you're running low. Unlike a relationship with a single individual, Facebook is more like a tap that can be turned on and off as needed, since you can have as many or as few discussions as you want whenever you want.

In general, I prefer to do things whenever I want: sleep, meals, exercise, work, etc. If I have a set schedule, then there are times when I wish I was doing something different, which is annoying and reduces productivity. For example, I might be hungry but have to wait until a set time to eat, as a result of which I may be distracted by hunger. Or, worse for my waistline, I might not be hungry when it is time to eat. And so on. Living with another person removes some of the freedom to optimize for one's own needs at any given moment.

Universal love

When I fell in love, I was surprised at the depth of my response to the process. I didn't realize that I would feel so strongly, since historically I had shown less interest in intensely emotionally intimate interpersonal relationships.

  • When I was a kid, I told an adult, "I don't want to get married." The adult eyed me knowingly and replied, "You'll fall in love some day."
  • In 2006, a fellow student said, "Brian should get a girlfriend", and I found this amusing.
  • In 2010, a doctor asked me if I planned to get into a relationship, and I found the suggestion unrealistic, replying: "That would take too much time".

But eventually, when I was 1/4 of a century old, the love bug finally bit.

A friend of mine was also somewhat surprised by this turn of events. However, one of his friends was not. His friend said: "I always knew Brian was a romantic. He loves the worms!" (Here the word "worms" is a metonym for "suffering insects and wild animals in general".) While partially a joke, I think there's something to this comment. Romantic love and altruistic love clearly have differences, but they share the common "love" word for a reason.

One of the things I found most wonderful about romantic love was being able to share the inner world of another person, so much that I almost felt like she was part of my mind. I could tell her anything, be open about any feeling, and remove any awkwardness or misunderstanding through completely honest communication. I shared her emotional trajectories along with her. Josie Carey Franz and Fred Rogers have a wonderful song, "Then Your Heart is Full of Love". It includes this verse:

When your heart can sing another's gladness,
Then your heart is full of love.
When your heart can cry another's sadness,
Then your heart is full of love.

It continues:

When your heart beats for a special someone,
Then your heart is full of love.
When your heart has room for everybody,
Then your heart is full of love.

The lyrics transition from discussing romance-like love for a particular person to universal love for all sentient creatures.

One of the wonderful aspects of romantic love is that it generates feelings that can be transferred to other organisms. While seeing how precious our partner is, we can also can see how precious everyone is, because we are all part of the same universe, behaving in similar ways, and having experiences that matter to us. At the end of The Dark Crystal, the protagonist, Jen, holds his downed female friend, Kira. A light creature watches and says: "Hold her to you, for she is part of you, as we all are part of each other."

Of course, it's important to translate these feelings into action. Empathy purely by itself does not reduce suffering. But these warm, loving feelings can play an important role in our mental attitudes toward altruism work and represent a helpful supplement to the distress and anguish that we experience when thinking about terrible suffering. We can want to reduce extreme suffering both because it's indescribably awful and because we deeply care about and feel part of those whom it afflicts.

I feel spiritually satisfied knowing I'm doing a decent job at helping relieve suffering in the world (in expectation). This is the most important goal in life, to which everything else has value only instrumentally. Even love -- as magical as it is -- can't compare in intensity to the horrors of extreme suffering that we need to work against.

Reducing suffering was Russell's third passion:

Love and knowledge, so far as they were possible, led upward toward the heavens. But always pity brought me back to earth. Echoes of cries of pain reverberate in my heart. Children in famine, victims tortured by oppressors, helpless old people a hated burden to their sons, and the whole world of loneliness, poverty, and pain make a mockery of what human [and animal] life should be. I long to alleviate the evil [...].

Love is a gift that life gives us as we pursue our real purpose in this world: reducing and preventing agony by the least fortunate sentient beings.