Could someone please tell me what would make ex-CIA director Gen. David H. Petraeus risk everything by getting involved in an extramarital affair?

That's the million-dollar question a whole lot of us have been asking ever since the eyebrow-raising news broke that Petraeus had been involved with Paula Broadwell, his biographer. Since no one besides the involved parties is privy to the inner workings of Petraeus' mind or that of  Broadwell's, attempting to explain it would be mere speculation.

But that doesn't stop folks from trying. Dr. Carole Lieberman, a psychiatrist and the author of Bad Girls: Why Men Love Them & How Good Girls Can Learn Their Secrets,  has made a career out of studying the inner workings of affairs the heart. She said, Broadwell, an accomplished married mother of two and Petraeus' biographer,  may have attracted the 60-year-old, four-star general's attention "by making him feel like the biggest stud on the planet. You would think that someone like him would already feel like the biggest stud on the planet. But his achievements were career related, not as a woman slayer or lady slayer.

"Plus, there were a number of things that they had in common – running, their education. She also flattered him by writing his autobiography," added Lieberman whose website is  "What more could a woman do to make a man feel like the biggest stud on the planet? She went as far as going to Afghanistan. She put herself in danger to get this man. She was hot for this man. She was willing to go all out…It gives new meaning to the name of his book, 'All In: The Education of General David Petraeus.'"

Petraeus' relationship with Broadwell went public last week following an FBI investigation into harassing emails by Broadwell to Jill Kelley, a Petraeus family friend from Northeast Philadelphia. It's unclear what Petraeus' relationship was with Kelley, but, no doubt, we'll be hearing more about that before long.

"She's a smart lady. She certainly knew that by writing those emails to that other lady...that this would expose him or that this woman would expose him, which she did," Leiberman theorized.

Meanwhile, Susan Shapiro Barash, author of "The Nine Phases of Marriage: How to Make It, Break It, Keep It," expressed surprise at the Petraeus-Broadwell affair's ever having coming to light.  "Based mostly on my research, wives are very good at keeping their affairs a secret."