Well, I don't want to be slapped over the wrists for saying this because I'm not into sexism of feminism what so ever.

But in my general observation in teaching - female students really do tend to hold onto things for a lot longer and remember significant events and what was said; long after the event in the classroom has happened.

Boys, on the other hand, after a really tough lesson the day before where one of them has told me to Eff Off (school's got extreme behaviours) they'll say "Good morning Miss" with a huge smile on their face; almost forgetting nothing about what had transpired before.

As much as I am reading about the issues with your gf, my first thought that came to mind is - what support are you getting in terms of looking after yourself when she goes through bouts of depression?

Okay given that before you made this post there was a heated discussion over an event that happened a long time ago. This whole thing over a time when leftovers were thrown away sparked a major event and eventually landed up with you leaving the house. I think your issues are a lot more complicated than just her depression.