"Learned helplessness" was an early concept when domestic violence first became the subject of serious study. The concept is that when someone learns that whatever she does, she can't control the inevitable violence, she becomes too afraid to even try to do anything to escape or to better her situation, or to hold the abuser accountable, because internally she feels the abuser cannot be stopped.
I worked closely with a woman who endured 25 years of abuse (only a year and a half of it physical, but it was probably the most sadistic physical abuse I ever came across). She completely believed all of his threats (not without reason) and was too frightened and helpless even to tell anyone what was going on until it came to light and someone helped her to plan her escape. Throughout the criminal case, she was POSITIVE he was SO smart and powerful (as he had taught her) that he would find a way to get out of it. Even when he was sent to prison for a lengthy sentence, part of her is POSITIVE he will figure out a way to get out of it. He taught her that. He constantly told her she was stupid, and he was smart, and that she couldn't get along without him. She was completely brainwashed. Thanks to some excellent therapy, she is finally healing a little bit at a time.