"If you know anyone who is colorblind," said the late psychologist John Money, "then you have a good idea of what it means to be love-blind." What Professor Money is talking about isn't the starry-eyed young person who falls in love, but the individual who seems entirely normal--social, friendly, and handsome or attractive, but who just never seems to fall in love with anyone. Believe it or not, love-blindness is but one of a broad spectrum of romantic problems now believed to result--at least in part--from chemical instabilities or malfunctions in the brain.