My ex (and thus far only foreveraloneectect) girlfriend had (has) depression, so maybe it's a tad unfair on her given that that disease just does make you go completely irrational over the stupidest shit and you don't get much control over it, but god-damn it got annoying sometimes. Thankfully I managed to avoid most of her anger being directed at me, but I still had to placate her a lot.
The best one though (and again this wasn't at me but I was used to comfort her) was when she got mad at someone for suggesting she liked another dude more than me... or at least that's how she told me it went down, when she was raging at me about it. Turns out, she had actually said it to them, then when they, in the same fucking conversation, turned around and said that it made sense as there were hints, that made her really angry, to the point where she stopped talking to them, came and raged to me about it whilst lying to me the whole time, claiming she had no idea why they'd think that.
Also you could never disagree with her, like once she was playing scrabble with her mum, and her mum made a 7 letter word (which is a good move for those not in the know) and when she told me, saying her mum had "ruined the game", and I suggested that it was more the case of her mum, you know, playing the game like you're meant to play it, this apparently made me the worst villain in the world.