After six years of dating, and one year engaged, Carol, 41, of Winter Park, Fla., felt something was off with her fiance. She noticed his Facebook profile had a thorough recounting of his life but didn't mention her. She also noticed he had a new female Facebook friend from the Florida Keys, where he had recently gone on vacation while she stayed home - a house they owned together - to plan their wedding.
When Carol (whose surname is being withheld) expressed her concerns, he said he wasn't sure he wanted to get married, she said. So she gave him back the ring and told him to ask when he was ready.
That didn't make it any less painful when, later that month, she said, she snooped in his email and saw a long message from the aforementioned Facebook friend describing a sexual relationship that had turned emotional.
"My world was just rocked," Carol said. "I felt that I had lost my whole purpose."
No vows need be exchanged for cheating to devastate people who believe themselves to be in committed relationships, a steadily growing demographic as couples put off marriage longer or decide they don't need a wedding at all.
The number of unmarried couple households, which includes both same-sex and opposite-sex couples, grew 41 percent between 2000 and 2010, from 5.5 million to 7.8 million, according to the U.S. Census. They represented 6.6 percent of all households in 2010, up from 5.2 percent a decade earlier, while the share of husband-wife households fell from 52 percent to 48 percent in that same time period.
Without formal legal ties, conventional wisdom would suggest it's easier to bail after infidelity tears through the trust and intimacy that hold a couple together.
And sometimes it is. But rarely is the post-affair path clear-cut.
Limited research exists on the prevalence and/or tolerance of infidelity for committed but unmarried couples. A study published this year by University of Denver researchers in the Journal of Sex Research followed a nationally representative sample of 993 unmarried individuals in committed opposite-sex relationships to explore predictors of first-time infidelity. It found that 14 percent had "sexual relations" outside of the relationship over a 20-month period, and 43 percent of those broke up after the infidelity.
People who cheated were most likely to have: parents who never married; problematic alcohol use; more prior sexual partners; lower relationship satisfaction; higher levels of negative communication or psychological or physical aggression in the relationship; lower dedication or no plans to marry the partner; and greater suspicion that the other partner was cheating. Notably, the frequency or quality of
the couple's sex life did not raise the risk of infidelity, nor did cohabitation decrease it.
More research explores cheating within marriage, which has become less tolerated in society.
Eighty-one percent of people of all relationship statuses polled in 2012 said extramarital sex is always wrong, up from an average of 70.5 percent of people who said so in 1973 to 1980, according to the National Opinion Research Center's General Social Survey, a widely used sociological poll based at the University of Chicago. A Gallup poll earlier this year found that marital infidelity was at the bottom of the list of morally acceptable behaviors - lower than human cloning, polygamy and suicide - with 91 percent of respondents considering it morally wrong.
Yet the prevalence of cheating among married couples hasn't budged much. About 19 percent of men and 12.3 percent of women in 2012 said they'd had sex with someone other than their spouse while married, about the same as it was 20 years ago (though there's been considerable variability year to year), according to the General Social Survey. That's likely an underestimate given the reluctance of people to admit to affairs and the survey's narrow definition of infidelity as sex.
Rather than rush to save or end a relationship after discovering infidelity, couples should take time to understand why it happened and ask: What is it about this person that is good for me? Clinical psychologist Janis Abrahms Spring, author of "After the Affair," offers tips for rebuilding a relationship:
-Write apology letters. After the hurt partner "talks about their hurt with an open heart," the cheating partner should write a letter spelling out exactly what he or she is sorry for. And vice versa. Letters are important because they demand more thought, and often people want to read the words over and over.
-Engage in trust-building behaviors. That could mean the cheating partner hands over cellphone records or promises to reveal immediately if the affair partner gets in touch. "Trust and forgiveness are not gifts from the hurt partner," Spring said. "They must be earned."
-Filter the discussion. It's tempting to ask for every gory detail, but consider if that's helpful, or re-frame the question to be about the couple rather than the third party. Be careful not to go on and on, which can alienate the unfaithful partner and deter conversation. The best way to communicate is to speak genuinely, honestly and briefly, with the listener mirroring back what was said, so he or she feels heard.