Omg a "sexless marriage" with 4 kids under 6? The last one born, what - 9 months and 2 days after the one before him? Please. No one would believe that - not even a total nitwit. I wonder if she's just making some cash by selling a story.
Not that I doubt Dean is still a cheater. I read his first wife's book and then I also read Tori Spelling's book that mentioned that time. Something about how his wife was sitting by the pool, late in their adoption cycle, and he tells her he's fallen in instant love with Tori and his wife thought he was joking, as he'd been making all kinds of unkind remarks about how ugly Tori was when he realized he'd be working with her. And then his wife decided to adopt the baby on her own, right? It's been a long time since I read about that, but it was something like that.
So yeah, I think Dean very easily gives himself permission to screw around, especially on "set", though I find it hard to believe he actually gets work.