Affairs actually improve marriages, 77 percent of cheats claim.
And two-thirds of love rats say they have a happy relationship, despite playing away.
Just 33 percent of those having flings said they were in an unhappy relationship.
The study of 2,000 married cheats revealed that the women were more likely to say they were still in a happy marriage — 71 percent, compared to 63 percent of men.
Men were more likely to think an affair improved their marriage, with 81 percent saying a fling was good for it against 72 percent of women.
The survey also found that, despite admitting cheating on their partner, 94 percent would be furious if they found a spouse doing it to them.
Jessica Leoni, of dating site Illicit Encounters which did the research, said: “I’m not shocked that happy people cheat.
“If you’re unhappy, your mind is elsewhere — there’s no way you can compartmentalize an affair. Adulterers don’t want to leave their partners, they just want some extra spice in their lives.”