@skinut68,
You CAN, however, set some boundaries. You can say, "We can go, but 2 drinks is the limit and if you agree to that but go over the limit, I'm leaving you there". If she goes over her limit, just leave. You can also video her next time she's falling over, etc., and show it to her. I had to do that with my ex. He was mortified. She can dilute her drinks with soda. But if she "can't" stop, she has a problem and just be aware of it.