Most of the alcoholics I've known are people with a ton of potential. They aren't (or weren't) failures at life because they lacked intellingence, wit, and ability. They simply couldn't tap into it while the disease had them by the throat. The road to alcoholic hell is paved with wasted (in both senses of the word) potential.
Just a heads-up. If it turns out she IS an alcoholic, it won't be as simple as packing her off to a rehab or AA to get well. Alcoholism is very complicated, and the alcoholic only sees that you are getting in the way of what she wants to do and interfering in her life.
Please keep posting here, the support is awesome.