<human>: Me and my girlfriend have a great relationship, we love each other and like each other very much. We recently went to visit a college as we are both graduating in a year, and on our way back we stopped at a whataburger to eat.

Everything seemed ok, until when we were leaving. I noticed that she was acting kinda quiet, and when we got back on the bus to go home, she had tears rolling down her face. I comforted her as best I coukd, and asked her if she wanted to talk about it and she said no. I figured she just needed some time, so she snuggled up next to me and fell asleep for the rest of the way. She was in a much better mood for the next day, and tonight (she broke down on a Thursday night) I asked her again if she wanted to talk about it. Again, she said no. I asked her if she was sure, and she got really upset and went to bed. She demanded that I never bring it up again, so i agreed to not talk about it. 

Since then, she went to sleep but it's killing me. I know I shouldn't mention it if she doesn't want to talk about it, but I have a bad habit of not knowing when to stop when it comes to things like this. I mean, I really care for her and I want to know what was going on, but I know that she will become very mad with me if I mention it at all. 

I should just try my hardest to not talk about it, right? As much as I'd like to know, Id rather not have her be upset with me. Am I doing the right thing?

Can you condense the text into three sentences or less?
<bot>: Girlfiend randomly started crying and I don't know why, and she refuses to speak about it. Should I just drop it?