Serious problem is that he DID cheat, before they married. Blatantly, boldly and with malice he let her discover his affair with a coworker. With her lack of self-esteem, she fell back into his circle of lies, as he knew her future held much more promise of fame and wealth than his would ever do.
He "fed" on her sad weakness of emotional fear and as they married, he cut her off and encircled her with his world only. Her contact with those that care, is gone...and she still lives with doubts and now no one to open up to.
A hard reality for many women, who become too weak to WALK away from deceit and lies.