"The couples counselor Harville Hendrix has written that the entire experience of falling in love can be distilled down to just four characteristic emotions. The first, he says, is a feeling of recognition--the thing that makes you say to your newfound love (the quotes are his), "I know we've just met, but somehow I feel as though I already know you." The second is a feeling of timelessness: "Even though we've only been seeing each other for a short time, I can't remember when I didn't know you." The third is a feeling of reunification: "When I'm with you, I no longer feel alone; I feel whole, complete." The fourth is a feeling of necessity: "I can't live without you." This is Aristophanes all over again. We speak of our partners as if they were a long-lost part of ourselves--and, accordingly, we are certain that they will be with us forever. We know they will never cheat on us. We know that we will never cheat on them. We say that we have never felt so understood; we say that nothing has ever felt so right. What is remarkable about this idea of love is how deeply entrenched it is--in our hearts as well as our culture--even as it utterly fails to correspond to reality. We fall out of love left and right. We question whether we were really in it in the first place. We cheat and are cheated on. We leave and are left. We come to believe that we never truly knew our lover after all. We look back on our passion in the chilly dawn of disenchantment--in the after-afterglow--and are so baffled by our conduct that we chalk it up to something like temporary insanity."