Let’s get something straight: You are not some fedora-tipping Man of the House who comes home from the office expecting the rump roast to be on the table. Nor are you an aging frat boy who sits in front of the flat-screen with an Icehouse while wifey irons your Red Wings jersey. You are sensitive. You were raised by a working woman. You wipe down the counters after you make the kids’ lunches. No decent woman would cheat on a man like that, right?

That’s what Rob (not his real name) thought, anyway. The 41-year-old financial analyst had a house in the D.C. suburbs, two kids, and in his own words, a “goody-two-shoes” wife from a nice Catholic family. Last fall, Rob’s wife began to seem depressed, “like something was bothering her and she wouldn’t tell me what it was,” he says. In December, after stumbling across some e-mails, Rob found out exactly what was bothering his wife: She had reconnected with an old flame. She’d been reconnecting with him for five months.

“It’s far worse than you can possibly imagine,” he says. “It’s like, What the fuck? The person you thought you married isn’t that person anymore.”

The tired old paradigm of the buttoned-up father who comes home late with the secretary’s Revlon on his collar has reached the end of its shelf life. Statistics vary, but it doesn’t look good: According to a study published in the Journal of Couple & Relationship Therapy in 2002, 55 percent of married women engage in extramarital sex at some time during their relationship (compared with 60 percent of men). And here’s a far scarier number: After interviewing more than a hundred adulterous wives for her 2001 book A Passion for More, Susan Shapiro Barash found that 90 percent of them didn’t feel guilty about doing it—they felt entitled to do it. Somehow, the 21st-century husband’s noble attempt to be provider and nurturer—a Superdad duality his father probably never attempted—seems to have backfired. Rob is the perfect example. He grew up watching his dad’s philandering wreck his parents’ marriage and vowed not to make it a legacy, only to find himself a cuckold a generation later. And he didn’t suffer alone. He had a nice support network on the website survivinginfidelity.com of guys who had gone through the same thing. “It’s so common, I wonder how many affairs go undiscovered,” Rob says.

“There are a lot of reasons why women cheat now, and the simplest is that they can,” says Diane Shader Smith, the author of Undressing Infidelity: Why More Women Are Unfaithful. “Nowadays women have jobs. And if they’re home, there are gardeners, there are pool men. They have opportunities and they feel empowered.” They also feel sexual. And while your prowess with a Dyson is commendable, it’s hardly titillating.