Gratification is more important to the mouse then being hurt. The same thing is true for people who go back to abusive relationships. They are addicted to that gratification, and don't step back to see the whole picture. Why do you think so many women go back to abusive husbands? Because they get high off of kissing and making up!
Yes it is possible to be addicted to pain. It's especially hard when the person you go back to is enabeling your behavior (they are no better).
Here's the thing, don't let yourself become addicted to trying to save these people, they don't want it. Come to that conclusion and save yourself alot of heartache and pain. Instead of becoming depressed, like I was for years. It's so not worth it.