stick with her for now. it'll probably pass. my gf right now, for the first month or so was in a really emotionally unstable state. long story short, her family's mormon (i'm not) and she was too, but she had problems with a lot of the beliefs. she was afraid to actually question things though because they teach you not to, and at first there came some theological differences between us that caused a lot of strain. that combined with the way that your average-joe-mormon raises a child stressed her out a lot so she cried every few nights we were together. i stuck with her, REASSURED her (important) with actual, thought out, logical reasons why things would work out for her.
now, you can see how much happier she is and how things have eased up with her parents (btw, she got the hang of questioning things and is no longer a part of the religion)