Its often been said we date and marry the people we think we deserve. If we use that premise as the foundation for looking at this situation, you can see where her past experiences reinforce this need to be with people who give her a prescribed outcome. Unfortunately you can not do anything to change that. There are so many variables that play into that situation and I would be willing to bet they go all the way back to her formative years as a child. So its really up to her to step outside her situation and see she is stuck in a pattern that will always give her what she expects. Whether or not that is what she really wants is another question. But for her, that is the nature of her reasoning and what allows her to justify her life choices. All you can really do is just be there in a supportive capacity when its possible. My deepest sympathy.