I feel like she's just overly rude. It's essentially "my goal in life is to make you feel as bad as possible about your height complex". And the way she invited him out. It also doesn't really make sense why he'd agree to go out with her given what we've seen so far. They barely have any sort of relationship, this being chapter 7 and each chapter being like 4 pages, so why'd he just go along with some random cunt acting like she's his boss?