Still working on the doormat thing

I'm still working on not being taken advantage of. It's hard to walk away from people and just let them be even when they don't take care of you or help you. Why is that? Why do we want to hold onto people that hurt us? As human beings, we're so self-defeating. Battered women stay with their boyfriends/husbands. We tell ourselves we can't do things. We set ourselves up to fail. Why? Do we all secretly hate ourselves? Or maybe just each other at times? Who can really know?