Yes, it is my opinion that a man who has changed two or more wives will continue with this process because it is not in his nature to be a faithful husband. Why should he be? Every woman in the world wants to be with him and his time is passing.
No, he was not cheating on her, unless there is proof. It is too easy for the public to assume one thing happened or another, but they are two people who should be allowed to keep secrets from tabloid magazines. We should not assume anything until the evidence is revealed.
Brad Pitt could not cheat with anyone and get away with it. He would never be able to trust that anyone he cheated with would not want to sell their story for money. They probably just broke up because they spent too much time together and got sick of the others' personal habits.
It is not of my business and I don't really care why or how Angelina Jolie decided to file for divorce from Brad Pitt. It is sad that relationships cannot last like they are supposed to. Marriage is supposed to mean something, but it no longer seems to. But it is between them.