Marriage strips away the illusions about sex pounded into us daily by the entertainment media. Few of us live with oversexed supermodels. We live instead with ordinary people, men and women who get bad breath, body odors, and unruly hair; who menstruate and experience occasional impotence; who have bad moods and embarrass us in public; who pay more attention to our children's needs than our own.

We live with people who require compassion, tolerance, understanding, and an endless supply of forgiveness. So do our partners. Such is the ironical power of sex: It lures us into a relationship that offers to teach us what we need far more—sacrificial love.