what do i do? im already tired of the way she is but i still love her

well, my girlfriend is a really good girl and ive been with her for 2 years. We' ve always been together and when we tend to have a fight its a weird thing. If im mad at her, she tries to switch the argument on me, doesnt tell me anything to make me feel better or the usual; that i have to understand. Ive been really patient all this time and like i said even when im mad, i have to go and apologize to her. if it was up to her she wouldnt tell me anything in the whole day. Lately ive been telling her tha im really getting tired of her and i talked to her and had a really good conversation. I told her to look at other relationships and find out who else from the people we know treats their wives or girlfriends as good as i treat her. She sat there quietly and said that she really apreciated me and that she would change about the way she was. Now like i said, ive been telling her that im tired and that im gonna leave her and she acts like if nothing is happening. Sometimes she does get scared but most of the time, she gets it as some kind of routine. What do i do?