Do you think its possible for someone to change their ways? Or is it all false promises until things finally break loose?

They have to actually want to change. And they have to want to change because they realize they do not like who they are.

If they say they will change in order to keep someone around they don't actually want to change they just to keep that person around. Their change will stop when they no longer feel in danger of losing that person and may even revert.