She was having a really bad week (she's on the verge of quitting her job & the stress is killing her) and me just taking off alone, going out and doing a small amount of drugs (without her), apparently really hurt.

I think communication was the main issue, she was bothered by me going out, but she didn't tell me (afterward she was like, yeah maybe I also wanted to go, but she didn't say and just went to bed all of a sudden) & I didn't tell her that I really needed to go out and reset my mind (also didn't really explicitly invite her). But it was good that we had the fight, at least now I know what the issues are & we can work on them. Also just healthy to fight once in a while :P .