Jay Welcome to the forum. This is a friendly and supportive place.
IT has taken a while for your post to be answered, this has nothing to do with your post, it is valued. Alas these things happen.
You are concerned for and worried about your girl friend.
It is hard when a loved one is suffering and you feel so helpless in trying to help.
When I was depressed I would push people away and refuse help and I did not want to talk about how I was feeling as I thought I would bring other people down.
Our girlfriend is under so much pressure with her studies, trying to keep the relationship going when she feels totally lacking motivation, and does not like herself. She may be pushing you away saying you are just a friend to protect you from being hurt.
Beyond Blue have excellent information on looking after yourself as a person that is providing (trying to) care for someone with depression.
Your health is important. You can only do what you are doling. Click link below
Would you be able to see if your girlfriend would ring the Beyond Blue support line 1300 22 4636
Sometimes talking to a trained person that you don't know can be easier than talking to someone you know.
These are just some suggestions.
Feel free to keep posting here if you want.