In the novel Captain Corelli's Mandolin, an old man is talking to his daughter about the secret of marital love between he and his late wife. He tells her:

Love itself is what is left over when being in love has burned away, and this is both an art and a fortunate accident. Your mother and I had it, we had roots that grew towards each other, underground, and when all the pretty blossoms had fallen from our branches, we found that we were one tree and not two.