Big Mak

I've dated quite a few girls and even been married once but I'm still confused on this question. Have I just not found the right one yet or is there something more to it that I don't know?

At what point is it ok to say it's not working out? I've been with this girl for 9months and she's got a son and $$$ issues and really wants me to marry her but I'm not ready for that. I have 2 kids of my own and a ex-wife that likes to make my life hell. I really love my girlfriend but sometimes all the drama of her life and all her physical ailments really gets to me. I don't know what to do cuz they say you should fight for what you want but how do you really know that this is what you want? I try to be supportive but sometimes the drama is too much and I just need some time with my own friends and not with her. Is that bad?