It's a double-edged sword for me because not only do I worry that the relationship ended due to her "losing feelings for me" as she put it, but then I just wonder if that is true or it's her trying to eliminate an obstacle on her pathway back to alcohol.
Not to sound harsh, but...it doesn't really matter. If she wants to end the relationship, then just accept that. She drinks. It doesn't matter if she says that stuff because she's drinking or not. She drinks. She wants to be free to drink and not have to deal with your reactions or whatever the case may be. Again, my advice is to let her go. You will never understand an alcoholic's way of thinking and you'll drive yourself mad trying to.