Some went online for a quick "sex fix," while others established more meaningful connections where they talked about personal problems and marital issues, Mileham said. Still others wanted to engage in cybersex, exchanging sexual fantasies with someone while masturbating, she said.
The vast majority said they loved their spouses but sought an erotic encounter online because of boredom, a partner's lack of sexual interest or the need for variety and fun, Mileham said.
One can reveal the most intimate emotional and sexual details to an unseen stranger at any time of the day or night, she said.
Several participants indicated they divulged more about themselves to online partners than to their wives or husbands.
"We need to better understand the contributing factors if we are going to be able to warn people about the slippery slope that starts with online flirting and too often ends in divorce." With the exception of two of the study's participants, all hid their online activities from their spouses, often "chatting" after their husbands or wives had gone to sleep, Mileham said.
But some used this form of effortless escapism while their spouse was in the room, she said.
"We started chatting about life, our marriage, what we like to eat, what sexual positions we like the best," wrote one man to Mileham.
"I felt like I've known her in another life." Mileham believes the time has come for the Internet to become as essential a part of pre-marital discussions as is whether or not to have children.
One 66-year-old man ended up having 13 affairs this way, she said.
Mileham conducted in-depth online interviews with 76 men and 10 women, ages 25 to 66, who used Yahoo's "Married and Flirting" or Microsoft's "Married But Flirting," Internet chat rooms geared specifically for married people.
The study's participants, who represented every state, included stay-at-home mothers, construction workers, engineers, nurses and presidents of large corporations.
Eighty-three percent of the study's participants said they did not consider themselves to be cheating, and the remaining 17 percent deemed it a "weak" form of infidelity that was easily justifiable, she said.
Other research has shown, however, that most spouses feel as betrayed, angry and hurt by online infidelity as they would if skin-to-skin adultery had taken place, she said.