Hi William and welcome to the forum -
I'm really sorry you're going through this. Considering this has been a pattern, it's possible your girlfriend is prone to alcoholism/addiction and if so, she will put her drinking first (at least until it too painful for her to do so).
Have you ever looked at AlAnon material or been to a meeting? (AlAnon, as opposed to AA is for people who care about the alcoholics in their life - it teaches them coping skills, how to detach, etc.)
There also a family/friends forum here - you may want to take a look there as well:
Friends and Family of Alcoholics - SoberRecovery : Alcoholism Drug Addiction Help and Information
I wish you all the best.....