Am I overreacting? Is there a way to deal with his drinking and running away from arguments?

My boyfriend and I have been together for 5 years and are both 24. We moved out together about a year ago which only lasted 6 months because of his constant drinking and deserting me whenever we had a fight. When we would have 'these' fights he would storm out, not answer my phone calls and not come home until the next day sometimes still drunk to the point where he would come home and throw up. I've told him that's it's over many times but he always comes back about a week later saying that he will change which lasts for about a week. I don't want to end the relationship because I think we do care about each other, but just that he doesn't know how to deal with emotional issues. Does anyone have any experience with this?