I don't think the ending had anything in particular to do with anybody being an asshole.
Risa liked stuffed animals because they were cute.
Izumi liked Risa because she's cute.
Nakabayashi (the guy) criticized Risa's fondness for cute things, saying she only cared about appearances.
Risa apparently gave up on stuffed animals in order to appeal to Nakabayashi.
As Nezchan described, Izumi felt her own attraction to Risa was shallow, because of how easily Risa gave up on her inner character (liking cute things).
The ending comes as Izumi discovers that Risa hadn't given up her love for cute things after all, and was still the same on the inside. Risa's love for cute things is an integral part of her, because (as Risa says) she's "a girl". Izumi decides in the same way not to give up on her love for Risa, because that's also an integral part of her. So the ending is about Izumi calling up Nakabayashi and telling him to let her come along so she can harass(?) them on their date.