Specifically, Angelina scolding him for not being at Quidditch try-outs and telling him he should get his priorities straight. Harry says that it wasn't his choice that he can't make it, but Angelina doesn't listen. She says he should convince Professor Umbridge to skip Friday's detention.
I felt bad and helpless at the way Harry was treated: he didn't have any control over the situation and I felt he was being treated unfairly. Even if you consider that he, arguably, had control over having been given detention because it was his outbreak in class that caused it, it was only one day's detention at first and I don't know whether he could reasonably have been expected to know it'd be four days in the end.
That kind of thing happens to other people, too—being treated in a certain way because of something you have no control over, and you can't even explain why you have no control over it because people don't listen to you. It makes me feel really bad ("oisairo'a" is probably the right term—roughly, "social discomfort"), mostly because I feel helpless.