This behavior takes many different forms, but there is one that may be relatively easy to work on if someone is helped to recognize this particular form of self-defeat.
Me: "…So what is stopping you from asking him for that raise?"
Caitlin: "I can't just go up to him and say, 'give me more money!'"
Me: "How do you handle it when your roommate eats all your food?"
Judy: "Nothing, really. If I say, 'why the hell are you stealing my goddamn food,' we’ll probably wind up fighting and that would be worse than just losing the food."