By Terri Orbuch PhD, The Love Doctorâ„¢

As a researcher and psychologist who’s been studying marriage and divorce for more than 25 years, I’m interested in the motivations of men who seem to “have it all” and then throw it all away, facing public humiliation in the aftermath and subjecting their families to the same.

Here are five ways to understand why men like Arnold Schwarzenegger, Tiger Woods and John Edwards risk it all to have an affair:

1. The illusion of invulnerability. Often, powerful men have affairs because they think they won’t get caught.  And even if they do, they believe they won’t get in trouble because they have the resources to cover it up.  These men often don’t worry about the long-term effects of their actions on others, only the short-term gains for themselves.

2. Ample opportunities for temptation. Wealth, fame and power are attractive to many women, who make themselves available to powerful men, sometimes aggressively and without scruples.  Then such men are away from home for days at a time, and the loneliness and the desire for female companionship can trigger infidelity.

3. Adrenaline dependency. Many powerful men have positions that require a lot of responsibility and authority.  They perform well under high stress and continually need and enjoy excitement or challenges to drive them forward.  An affair gives them the same type of exhilaration in their private life.

4. Enabled by yes men. Powerful men tend to be surrounded by people who protect them, idolize them, and even “enable” their vices in order to remain inside their influential orbit. Being surrounded by people who don’t challenge your decisions or give you honest feedback has an effect on your ego and your sense of propriety and limits.

5. Desire for change. Let’s not forget that powerful men are still men, and usually an affair signals an internal need for change.  Something in the man’s life or his relationship isn’t okay — and the affair creates the trigger for change.  Boredom and relationship ruts are common reasons couples cite for infidelity.

While influence, wealth and celebrity may present some additional challenges that are unique to powerful men, the fact is that not all such men succumb to infidelity.  And the explanations above are certainly not excuses for the behavior of those who do.

Terri Orbuch PhD, known as The Love Doctor, is project director of longest-running study of married couples ever conducted, funded by the NIH and ongoing since 1986. A practicing marriage and relationship therapist for more than 20 years, she is also a popular love advisor on radio, TV, and peoplemedia.com, most recently seen on NBC’s Today.  Her new book is 5 Simple Steps to Take Your Marriage from Good to Great (Random House). Learn more at www.drterrithelovedoctor.com.