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

Going for outside help concerning relationships is usually my *last* resort, but this issue is driving me nuts. 

Backstory: Been seeing a girl for about 7 months now; only been "official" for about 3. We're great together. Laugh a lot, joke with each other, blah blah. The only thing that bugs me is that she is fairly closed off and *sometimes* emotionally distant. The worst way this manifests itself is that if she's mad at me about something she won't tell me what it is. She won't even tell me she's mad. I can usually figure it out by the way she acts. Then she'll admit it, but won't tell *why* she's mad. Instead, she'll say I should know why. My reasoning to her is that I want to make her happy and stop doing whatever bothers her, so she should tell me. She responds with: "No, I don't want you to change. You should be who you are, and I either accept it or don't." In a sense I see her POV, but mostly it frustrates me because I think it's completely normal and acceptable to change certain things for a person you're enamored with.

So basically, I'm with a girl who feels it's more normal to keep issues bottled up until she explodes with rage and realizes she doesn't want to be with me. I, on the other hand, am of the opinion that relationships should be as open as possible and couples should be willing to change for each other if they want to be with each other. I guess I just don't know who to explain this adequately to her, and any help would be appreciated.
<bot>: Girlfriend won't tell me why she get's mad. Wants me to figure it out on my own. Very frustrating,