The most useful word I learned from David Brooks' The Social Animal is "limerance" - intensive love toward another with a strong desire for reciprocation. What we most desire is connecting with what we love. This is even more rewarding than completing the connection. The mind is geared more toward predicting rewards than the rewards themselves.
“So a happy life has a recurring set of rhythms: difficulty to harmony, difficulty to harmony. And it is all propelled by the desire for limerence, the desire for the moment when the inner and the outer patterns mesh.”
He reads limerence as melding together in harmony. It is not simply the fact of matching our map of the world, our information, with another person's that we value. We coat information with meaning, with emotional value. He cites a controversial theory that love is not an emotion, so much as a motivational state.
And what turns limerance at the individual level into a source of social structure is that we compete with others in order to connect. We can see this most clearly in the competition for mates, but it applies very broadly. We compete in patterned, predictable ways. These patterns are also information that we coat with meaning and emotion.