Going to bars and smoking pot together does not help someone stay off their DOC.
Case in point, I used to be able to smoke a little pot and go out to bars without having it turn into a rip-roaring nightmare. but then my addictions progressed and I got hooked on cocaine and eventually crack. I was no longer able to handle the bar scene. I was no longer able to use drugs recreationally or go out and "party" a little bit. As an addict, those kinds of behaviors lead me back to my drug of choice. In order to stay off cocaine, I have to stay out of those situations.
So I totally understand wanting to 'party' with your girlfriend like a 'normal' couple (and not have her get out of control) Unfortunately, it just may not be in her realm of ability anymore to do that anymore - no matter what you think or how you wish things could be.
Once you are a pickle, you can't go back to being a cucumber. It's a tough thing for addicts and alcoholics to deal with - and their sig others too. But that's the way it is.