Still don't get why those "friends" were so pissed with him hanging out with the girl
Like someone else said, they put her on a pedestal. This is exactly what the female MC was talking about, and the reason why she feels so exasperated. Also, this is why she doesn't consider them friends, since they just idolize her. The main reason why she liked the MC was because, for once, she was not idolized, but seen as an equal.
Personally, I don't like those tropes, but in these type of stories, they work like a charm because it helps the MC to man up and get past that.