Kirstie Alley's Book, 'The Art Of Men,' Highlights Actress's Infidelity (VIDEO)

What led to the demise of Kirstie Alley's first marriage?

On Monday, Alley sat down with "Entertainment Tonight" correspondent Chris Jacobs to discuss her new book "The Art Of Men (I Prefer Mine al Dente)" and opened up about the affair that led to her divorce from first husband, high school sweetheart Bob Alley, in 1977.

The former "Cheers" actress began dating Alley at age 16 and the two married four years later. By age 24, the then-couple had moved across the country from Kansas to California and not long after, Alley met a man named Jake. Although she admits she didn't have sex with him while she was married, she describes the affair of the heart as "worse than cheating" and insists she "destroyed [the] marriage."

"I think it gets worse when you fall in love with someone else when you’re with someone and you’re plotting and you’re planning," Alley said. "What I did do with Jake was I kissed him. In my world –- in Kirstie world -- that meant I had to get a divorce. Because that was unethical and that was infidelity to me."

Six years after the split, Alley remarried actor Parker Stevenson in 1983, but divorced him in 1997 after 14 years of marriage. She recently confessed that during her marriage to Stevenson, she fell in love with Patrick Swayze on the set of the 1985 TV show "North and South." She also admitted to falling for John Travolta while they were filming the 1989 movie "Look Who's Talking," but neither relationship ever became physical.

Alley is certainly not the first celebrity to fool around with someone other than her spouse. Click through the slides below to see which other divorced celebs reportedly had affairs with so-called "regular" people.