Well it could have started when she was in pain, and now that they have fought so much she just hates him. Some bullies just wont give up and once they are in that mind set there is nothing you can do to get them out of it. You can try taking them for walks together, you and your boyfriend together, just in case they fight you can separate them. Sometimes this works and sometimes it doesn't. I feel for ya, but you may have to just find her another home. We had a beautiful champion female that a handler let her crate fight and every since then, she hated all other bullies and we had to find her a good home with no other dogs, and now she is a happy girl.