I know a guy who is divorcing wife #3. She's leaving him because he cheats.

You'd think she'd have figured that out when she met him and he started sleeping with her while married to wife #2, who was also a mistress-turned-wife who couldn't take the cheating.
He likes to be married because he enjoys the company, sex and person who cleans. But he has no intention - even going into these marriages! - of remaining faithful. He tells them he does, but he doesn't. Everyone knows it!! Some even point it out to the wives-to-be, but do they listen? Nope.
He tries to just live with them, but they push for marriage. "If I don't marry her, she'll leave," he says. I tell him she won't and he says, "But she'll keep whining about it." I ask why he cares if they leave..."Well, somebody has to wash the dishes." He's kidding, but he isn't.
This wife asked me if I thought he was sleeping with someone at work and I said, "Probably. He sleeps with lots of women. He cheats on his wives...I thought you knew that when you married him." He was kind of mad at me for that, said he thought I was one he could trust to bring his girlfriend-wives around and asked me if I was going to do it again. ...because he's obviously planning to do this again.
Women who cheat with married men and end up marrying him and being mad that he cheats are just dumb.