They are just like everyone else
Men dally. It is the nature of the beast. I do not believe men were made to be monogamous.
Perceived power and money gives men a hard on...and women are just as guilty because they swoon over these men....and the women are MORE than willing to play the game.
I think there is a certain adolescent thrill of 'getting away with something naughty", too, that many humans never seem to outgrow.