For a lot of people, the garden-variety affair seems to come out of the fact they are dissatisfied in their relationship and they start to confide in another and that starts a slippery slope. With serial affairs, their attitudes about fidelity are different," says Kristina Gordon, an associate professor of psychology who conducts infidelity research at the University of Tennessee-Knoxville.
Gordon, co-author of Getting Past the Affair and Helping Couples Get Past the Affair, says many factors come into play but include a feeling of entitlement, which goes hand-in-hand with insecurity.
"A lot of folks do get that sense of entitlement because they have people telling them how wonderful they are. Some are very driven, and it's sometimes out of a sense of insecurity. They are continuously seeking someone to make them feel good when they can't do it themselves," she says.
Gordon and others who study infidelity say they aren't aware of any existing studies that differentiate one-time cheaters from those who have repeat affairs; it's not easy to get good data about affairs in general, they say.
"Overall, the best estimates are that between 15% and 40% of men will cheat at some point in their first marriage – best guess, 25% – whereas about 5% to 25% of women will cheat at some point in their first marriage – best guess, 15%," psychologist David Schmitt of Bradley University in Peoria, Ill., said in an e-mail.
A new study he co-wrote, just published in the European Journal of Personality, suggests that narcissism and other personality traits affect short-term mating.
Todd Shackelford, a psychology professor at Florida Atlantic University in Davie who directs the Evolutionary Psychology Lab and has been studying infidelity about 20 years, agrees that personality traits linked with infidelity go beyond just narcissism. He says people who have low scores on personality tests measuring conscientiousness, as well as high scores on openness to experiences, may be more likely to be unfaithful. But although personality traits are linked with infidelity, they are not very powerful predictors, he says.
For men, he adds, it's all about opportunity. And for celebrities, athletes and others in the public eye, it's all about having the money to cheat, traveling away from home and having strangers throw themselves at you.
"Sheer opportunity is the single best predictor of men's being unfaithful. It's really that straightforward," he says. "Other things matter, of course, but a lot of work indicates it's just sheer opportunity, which doesn't seem to be as good a predictor of women's infidelity."
The parade of women coming forward to proclaim a liaison with Tiger Woods has brought a new twist to the typical cheating husband story.
The famous golfer's admitted "transgressions" and "personal failings" suggest his philandering is of the repeat variety, making this a tale about serial infidelity and raising questions about how such dalliances may differ from an affair that is often characterized as a one-time "mistake."
TIGER WOODS: Why are men unfaithful?
CONTINUING: As allegations go on, so does fallout
DISHAY COLLINS:They sud just be gay