If you want to stay together though, you should give her more attention. I'm not sure of her history, but it seems like she's lashing out because she's afraid of you drifting away. She seems afraid and senses that things are going downhill. If you want to change her attitude - you can talk all you want - but you have to show her through action that you are dedicated to her. I'm positive she senses your changing reactions towards the relationship, and it is obviously driving her up the wall.