Rob Lowe has compared being monogamous to turning down a glass of wine.
The actor has been sober for 21 years and married for 20 years to Sheryl Berkoff, a make-up artist he met on the set of Bad Influence.
He said of not straying: "I look at this like I do sobriety. To this day, the thought of never having a glass of wine is a life which doesn't really appeal to me.
"So each day I decide, today is the day I'm not going to have some wine. It's like that with my wife."
Rob, 47, enjoyed previous liaisons with the likes of Demi Moore and Princess Stephanie of Monaco.
The West Wing star and former Brat Pack member, who has two teenage sons with his wife, admitted: "I'm not sure we're meant to be monogamous, in fact I'm positive we're not. But day in and day out I choose to be with my wife. I know I'm never going to find anyone I love more, who's sexier or a better mother."
He said: "We're all tempted from time to time, particularly in the business I'm in. But we are never apart for more than two-and-a-half weeks and early in my career, she and the family always came on location.
"I've made real concessions in my life to do television as opposed to movies, which enabled me to be home when the kids were young. It's a recipe for disaster to have a newly-married young man on location and the wife at home. I've made choices to try to ensure my chances."