You thought Romeo and Juliet had it bad. When it comes to social disapproval, people who love a much younger or older partner face discrimination as intense as that encountered by interracial and same-sex couples.

Though Demi Moore's marriage to Ashton Kutcher, 15 years her junior, may have opened some minds, people in relationships with more than a 10-year age gap face frequent public scorn in the form of disapproving stares or poor restaurant service. "It's one of those biases that people find justifiable," says Justin Lehmiller, a Purdue University researcher.

Social disapproval can doom a budding romance because partners have fewer opportunities to "invest" in the relationship. Just as a woman dating outside her race may feel uncomfortable bringing her boyfriend home, so-called "May-December" couples tend to receive less support for their unions than other couples do.

Despite these hurdles, Lehmiller has found that age-discrepant partners are often more committed to their relationships than partners who are closer in age. He says, "They probably evaluated the costs going into the relationship."

Women are most likely to bear the brunt of society's reproach. Younger women are seen as gold diggers, while older women are scorned for trying to hang on to youth. Says Lehmiller: "Either way, men get a pat on the back."