afterschool talking

At first when these two friends talked to each other while walking home after school, it could be a little uncomfortable. In art class it was very relaxed and silly and they could say anything, but when they were walking home, she thought to herself, he can be a very nervous person. Once they were walking home from school and right before they got to his house she tripped over a curb. And if they'd been in art class maybe it would have been no big deal. But she started to get the feeling that he was going to try to make her feel better. He said, "Don't trip and fall. It would be very bad if you hurt yourself. I wouldn't want that." Which was a nice to say. For some reason she felt very embarressed. And she thought, "This world is so stupid." It was a nice thing for him to say, so why would she react that way (feel embarressed) and then think something angry (about the world)?