(LifeWire) -- Elizabeth Blackney says her heart goes out to Elizabeth Edwards, wife of former Democratic presidential hopeful Sen. John Edwards, because she's been there, too.
Expert says some people cheat only once and never cheat again.
Blackney was just 22 and pregnant when she found out in 1995 her husband had been having an extramarital affair.
"It occurred to me that I hadn't seen the phone bill come in the mail for a while," says the now 36-year-old mother in Bend, Oregon. A quick call to the phone company confirmed that her husband had requested the bills be sent to a post office box that she was unaware of.
After Blackney had the bills rerouted to their home address, she discovered what he was hiding: a long-distance relationship with another woman. When Blackney called the woman's number to investigate, she found out that her husband not only had a mistress, but that he'd told the other woman that Blackney had died in childbirth.
"I was horrified," Blackney, the political director for BlogTalkRadio.com, says. "It was almost sociopathic."
Shortly after her daughter's birth, Blackney's husband was deployed to the Middle East with the United States Air Force. Through letters and phone calls, they gradually reconciled. "I decided to forgive him," she says.
But fate intervened. In April 1998, he mysteriously disappeared before he was scheduled to board a plane in California to fly to Oregon, where the couple had planned to reunite. Several days later, his body washed up on the Pacific Ocean coast at Vandenberg Air Force Base, where he was stationed at the time. "No one knows what happened," says Blackney.
Blackney has never remarried or questioned her decision to forgive the infidelity. "As difficult as our relationship was, he was the love of my life," she says of her late spouse, who is buried at Arlington National Cemetery.
"I know people who have been married 30 or 40 years who don't know the moments of happiness that he and I knew in our brief but turbulent marriage," says Blackney.
The psychology of cheating
Infidelity can be brutal, but it doesn't always precipitate divorce, according to Pepper Schwartz, Ph.D., a University of Washington psychologist and chief relationship expert at PerfectMatch.com.
"I do think that marriages can weather this," says Schwartz. "But will they ever be the same? No." Watch insider on the affair and Edwards family »
So why do people have affairs? "There are hundreds of reasons," she explains.
Relief from tedium, says Schwartz, is a big one. "I've known women in loving marriages who claim that they have lost their sexual appetite," she says. "But then when asked if Brad Pitt walked in the room and declared his love, would they feel moved? And the answer is most always 'yes'."
Other times cheating stems from low self esteem or feelings of self validation. "They'll say, 'I've been a good girl all my life, now it's my time to have some fun'," she says. "Or, 'I deserve this one little thing'."
And like former Sen. John Edwards' admission that he had begun to regard himself as "special," Schwartz has seen many other men and women fall into what she calls the "king or queen syndrome."
"Some people get a sense of entitlement," she explains. "They say to themselves, 'I can do this without getting caught, without falling in love. Gosh, I deserve this, and I really want this'."
Women aren't the only victims
Men and women both have affairs, but not necessarily for the same reasons, says Mark Goulston, M.D., a marriage expert at Divorce360.com and author of "The Six Secrets of a Lasting Relationship: How to Fall in Love Again -- and Stay There." While men often break their marriage vows for reasons that include ego, a need for adulation and sometimes narcissistic behavior, he says, women tend to be tempted for different reasons.
"Women more often fall in love [with someone else] to feel adored and with a promise of protection and to ease pain," Goulston explains.
Rick Singer, 31, a writer who splits his time between Grand Cayman Island and Wilkes-Barre, Pennsylvania, says that when his wife had an affair last year, it caught him completely off guard -- especially since she had just given birth to the couple's twin boys six months prior.
"I thought we had trust in each other," he says. "I had had trust in her."
The news, which he learned of from his children's nanny, broke his heart -- and crushed his ego.
"I ended up checking myself into the hospital," he says. "The rage and hurt in my heart was so intense. I didn't want to do something stupid."
But he says he worked through his grief, and realized that he needed to move on.
Now divorced, Singer says he can't forget the pain he endured, but he has forgiven his ex-wife and today they have a cordial relationship. "Forgiveness isn't just for the other person," he says. "It's for yourself, too."
Reconcile or move on?
Should you stay or should you leave your cheating partner? "It really depends," says Schwartz. "It's important to distinguish between a dead marriage and a dead patch."
The key questions, she says, are: "Did you love each other before, and do you love each other now?" If the answers to both are yes, it's worth reconciling for. It's tough, she admits, but "I've seen people do this all the time."
A sign that a relationship is doomed? When you realize that your goal is to punish your spouse for their infidelity, says Schwartz, or when the cheating partner refuses to change.
"If it's a dead marriage, where you both barely even like each other, it may be fate's way of telling you to give up," she adds.
But, if you've been cheated on, take heart. "One of the myths out there is that if someone cheats, they're going to do it again and again," says Schwartz. "Most people just do it once, and never again. The guilt, the fear that their partner will find out -- it consumes them."
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