I read the raws, Katsura is actually confronting Ikkoku for behaving that way. Like they are an outsider. And Ikkoku said it was because she looked so sad the last time they go to karaoke together (when he firmly rejected her).
Ah.. I'm sorry, I did change some stuff around in the translation because it wouldn't make sense to English readers and the other raws I have; is missing some panels, I'm sorry for the miscommunication :(
I read the raws, Katsura is actually confronting Ikkoku for behaving that way. Like they are an outsider. And Ikkoku said it was because she looked so sad the last time they go to karaoke together (when he firmly rejected her).