Google the words "infidelity" and "discussion group," and you'll come up with more than 10,000 hits, including dozens of websites where people share their deepest, most painful marital secrets.,,—the list goes on. And the permutations are endless. On iVillage, the boards grouped under the rubric "relationship problems" include Married Without Romance, Betrayed Spouses Support, Betrayed Girlfriends Support, Cyber-Cheating & Emotional Affairs, Should I Stay or Should I Go, Life After Betrayal, Surviving Divorce & Separation, My Affair Support, and After the Affair. Infidelity chat rooms have become the agnostic equivalent of the old-school Catholic confessional. When the deepest trust in your life has been broken, you look for safety among perfect strangers.

The phenomenon of infidelity forums sits squarely at the intersection of morality, technology, and secrecy. Now that alcoholism and drug addiction are socially acceptable sins, infidelity is one of the few cultural taboos left. According to David Popenoe, founder and co-director of the National Marriage Project at Rutgers University, while infidelity is far more prevalent today, attitudes about it haven't budged since the '50s. "Ninety percent of people think fidelity is absolutely the basic part of marriage," says Popenoe. "It's almost a litmus test for success." Once cheating enters the picture, people can become as secretive with friends and family as an adulterer is with his or her mate, but Popenoe doesn't consider Web posts replacements for human dialogue. Rather, in an era of smaller families and looser friendships, the Web, he says, is a pipeline to a "huge group of people who have similar experiences."

On (a site that began as a place to discuss your kids but rapidly became a place to discuss anything family- and marriage-related), one woman contemplating an affair posted a cry for help. Another woman in a similar situation replied, "I never discuss this IRL [in real life]. Too personal. It's a shame, though, because so many of us go through things like this."

"Infidelity triggers everyone's morality," says psychotherapist Jane Greer, PhD, author of How Could You Do This to Me? Learning to Trust After Betrayal. "Loved ones are invested in your marriage; they can't give you nonjudgmental support. Yet being a victim or perpetrator of adultery is one of the times in a person's life when she most needs to talk—without the risk of anger, criticism, or blame. And that perpetuates the need to conceal."

So we type. And type. And type some more.