Girlfriend is upset with me?

I have been with my girlfriend for 8 months. The issue we are having in the relationship is me recognizing what she is upset about. If I do something wrong I get the silent treatment. She will never want to talk about it when I ask her whats wrong. We talked about this and its just what she does when she is upset. She wants me to figure out what is wrong on my own and to apologize. I try to figure out what I did wrong but I usually end up apologizing just in general and dint figure it out, or I do when she tells me. We have somewhat gotten past this but is there something I could do to try and fix this? Second, since this issue whenever she appears upset I ask her if its something I did, I guess I have trouble recognizing when I do something wrong. I tell her I didn't do anything to upset her I just want to make her happy.