She begged for me back and now is acting unhappy....help me out girls!?

We broke up and she was seeing someone else..then all of a sudden she started telling me she wanted me back and broke up with him...this is the second time she has done this with the same guy. Weve been back together and ive been worried about her doing it again and my paranoia is annoying her now. She has been ok but as soon as i try to talk about a concern she says " Can we just move past this, I made a mistake and i wont do it again...I dont want to talk about this **** anymore". I understand it may get annoying if were trying to work things out and all i talk about is "Are you going to do it again?" , and "Are you sure youre happy with me", and " can you please show me you love me". I might get annoyed to. I dont know though cuz weve been together for a few years now and she just wants to act like nothing happened and expects me to just be casual and relax like everythings ok. Ladies please give me some feedback if you kow what is going through her head.