I sympathize with you a bit because I also despise bars. The scene behind them, the kind of people that frequent them and everything.

It may also have something to do with the fact that my dad was a major alcoholic and would bartend on the weekends at a shitty dive bar and drag me along and leave me there to play pool and deal with the noise and other generally disgusting shit that goes along with being around a bunch of chaotic drunks.

For me personally, nothing good happens at a bar. I associate them solely with drunks and single people looking to find someone to fuck for the night. And if a girl with a boyfriend is out at a bar alone, its even more allure for other guys to get her wasted and take advantage of her. Conversely, no respectable girlfriend goes to a bar without her SO unless she has other plans in mind.

I would just cut her loose. Who knows what else she's lying to you about. Also. The simple fact that she apparently a super huge bar chick and youre not okay with that makes you fundamentally incompatible.