Need open minded answerers pleeeease...?

Ok I'm going to throw out two things first. Yes, I'm gay and I've been seeing a girl with a girlfriend. I don't need any lectures about karma or cheating, been there, done that, heard it. My question is this...I'm seeing a girl...who's taken...she's gotten caught many times. She is the type of girl who HAS to have someone, have that "main squeeze"...then when she gets bored, she is back to her promiscuous little ways. Well, we've been "seeing" each other for about five months now (holy sh**), anyways...I think I am too available. If she wants me to see her at work, I do, if she wants me to pick her up some where I do, any chance to hang out with her, I do. Well, I'm not getting any a s s from her lately, except a week ago, but she can't remember, because she was drunk. I wouldn't say I'm too nice, because her gf treats her like ****, and I don't "chase", most girls chase her, and I can tell she easily gets bored with that. I don't think I should bend my back for her, if I'm not getting any a s s....I was getting some here and there for a while...but it's always when we are intoxicated AND it hasnn't been LATELY...any suggestions?? Lecturing answers will be ignored..