Why do men and women cheat? For Darren Morgenstern, that question is more business than personal.
Morgenstern runs AshleyMadison.com, a controversial Web site that helps married men and women who want to have an affair -- but stay married -- meet potential partners.
One of Morgenstern's ads touts: "Some of us will always find a way to have multiple partners."
To answer the fundamental question at the heart of his enterprise, Morgenstern hired a woman named Felecia to pose as a someone seeking an affair and secretly record what her would-be paramours told her about their motivations.
Morgenstern shared the video with Primetime Live. The clients did not know about the taping nor did they consent to it, so their faces were concealed and voices were changed to protect their identities. But the dialogue is real.
On Felecia's first date, she met a man Primetime Live is calling "Rob."
One of the first things Rob said to Felecia is, "Honest to God, I've never done anything like this -- you are the first."
Rob was shy initially, but over time he warmed up and confided to Felecia that his sex life with his wife was boring. "I find that I'm getting in a rut," he said.
Felecia soon learned that Rob's lifestyle was working six days a week from early morning until late evening.
On another date, Felecia met someone Primetime is calling "Josh." He told her he had been happily married for 11 years, and he confided his motive for cheating: simple lust.
"Is it selfish?" Josh asked. "Hell, yes! I am being so selfish right now."
But he also said he didn't intend to leave his marriage: "Right now my kids are everything."
Morgenstern says many of his clients are asked, "Why don't you just leave the relationship?" But, he says, "It's not like that in real life -- there's assets, there's children, there's religious beliefs, there's costs."
However, Morgenstern's study did not only comprise men. On one of his hidden camera videos, a married woman looking to cheat was asked, "When was the last time you said you had sex with your husband?"
"Two years ago," she said to a male actor. "I have been sexless for two years."
So the answer to Morgenstern's question appeared to be simple: Both men and women said that they are trying to fill a void.
Nearly a dozen clients were interviewed on Morgenstern's hidden cameras and many gave answers similar to Josh, Bob and the woman: that they were trying to fill a void.
And with more than 250,000 subscribers, Darren Morgenstern has learned he can make a living on one unconventional principle with which many disagree.
"People change, relationships change, circumstances change. There are no absolutes, and you could get to a point in your relationship where it's just monotonous to remain monogamous," he said.