<human>: Can you condense the text into three sentences or less?

Currently I'm going through a tough moment in my relationship. We always end up in an arguement and last night I just had a bit enough of it. I simply went home (note: my girlfriend lives with her parents and I live on my own, she still studies) saying I need to think. The day after (which is today) I keep thinking about all the good things we did together, even though I know a lot of those moments together she was always grumpy... When I'm with her, I'm thinking: "pff, I should be better on my own, so I can make my own decisions, instead of always having stress making decisions, etc.", but now that I'm not with her and fear we are breaking up, I'm always thinking of the good stuff we did together (and that makes me cry :'( ).
<bot>: Why does my brains always make me think of all the good parts of my relationship instead of the bad things, resulting in me wanting to be back with her?