I got bitchy just reading this thread.
You don’t like how your GF talks to you or when she talks to you? Ok, how about YOU talk to her? Really talk to her–not cuss her out for taking you to task for something not yet done; not complain about her “bitchiness” when you seem to share the same trait; not “I don’t want to ruin a good mood with all this stuff.” BS.
Seriously–listen to yourself: when, exactly, is she supposed to bring stuff up? You don’t want to hear it when you’re already in a bad mood, and you don’t want to hear it and ruin a good mood? I suppose she could talk to you while you sleep, and she might get more out of it.
If she is as horrid and carping as you make her out to be, then leave her already and be done with it. If she is not, man up and find a time to talk to her–after dinner or mid-morning some Saturday. Say something like “I don’t like the way we communicate and I’d like to change it. How about we come up with a system to address both our needs?” and go from there. IOW, take responsibility for your half of the communication and tell her she needs to take responsibility for her half. Since you have not done anything like this for the past 6 years, expect some resistance on her part.