Eve Fairbanks, a writer who lives in Johannesburg, is at work on a book about South Africa.

Love’s labor isn’t always lost. (AP Photo/Muhammed Muheisen)

A long time ago, a man and I, in love with each other, argued about his lack of curiosity about the world. It seemed to me that more interest in others could make us happier, and more important, make him happier. He said no: he was happy as the homebody he was; this trait was elemental; it could never change. We each dug into our positions. The conflict swelled. We parted.

Eight months later, though, he returned to me. “I’ve become the person you thought I could be,” he said, with surprise and pleasure in his voice. He told me that soon after we parted he realized with a kind of thrill that it wasn’t so hard to change. He started learning to cook Korean food. He hosted diverse dinner parties. It was easy; it almost seemed to have happened without his will. He had become, he said, the exact man I had wanted to be with.

At the time, very young, I found it sad. It was too late for us. But then, a bit later in life, I found myself in a similar position. The desire my partner had for me to take control of my finances and love without reserve wound me up like a spring. As soon as we parted, it was as if the spring released, and I suddenly was able to become the person he’d hoped I could be: more calm, more settled, with a budget app on my phone, ready to love unconditionally.

The phenomenon is common. A male friend recently marveled to me that after he broke up with his girlfriend, in part for her defiantly parochial tastes, he observed with some bewilderment that she spontaneously began listening to his kind of music, reading his kind of books. My mother, a bohemian, pushed against her scientist father’s clinical nature. After he died, she told me, it was as if part of him went into her, and she began investing in the stock market. But only after he died.

Sometimes it seems like one of the bitterest tricks wrought on us by the creator of human nature: We can accept so many lessons after a parting that we struggle to accept while in the other person’s real, flesh-and-blood presence. And then we ask ourselves afterward: Why couldn’t I have budged just a little bit earlier, when it still could have made a difference to my loved one, when it could have created a common ground?

I have wondered lately, though, if what seems like a painful bug in human nature, yielding deep remorse, is actually a subtle tool used in the world by Love. In a mystical way, it actually allows our love to reach more people. If we could always grow with our lovers, what we learned would stay shut up in a closed system: the loop between us and our lover. The fact that sometimes we can only match and mimic a lover’s good qualities and rise to his fantasies after a rift means those qualities we have acquired go on to our next lover. Magically, my old boyfriend’s next girlfriend, whom I did not know, benefited from my curiosity, which he took from me, it turned out, as a parting gift. Thus love expands itself, replicates itself, deepens itself, spreads itself virally, passes itself from person to person, and continually grows in the world, even as we may lose.