Why did she break up with me?

She broke up with you because she dislikes the fact that you party every night and are constantly drunk. Personally, i understand her, she wanted to see you sober sometimes, and spend time with you. Besides, it's hard to communicate with someone who's under influence of alcohol all the time. Further more, drinking so much is extremely unhealthy and you're ruining your own body. Think about consequences of your actions sometimes. If you want to try to get the girl back, then you'll have to change for good.