I guess I'm actually among the minority here that doesn't mind this arc at all. It's not peak or anything, but I certainly don't dislike it.
Kyotaro was kinda perfect for navigating the jumbled mess that is college relationship drama. He investigated rumors, located key participants, got people to put their feelings into words, asked clarifying questions, and eventually untangled the web enough for Onee-chan to handle the rest.
After we've figured out that Dai-san is a cheating bastard hanging out with Momo the Ho and his girlfriend let her personal beef leak into the game of rumor telephone, Kana was essentially able to cut the drama out and clear the air for the band to move on.
Man, I love Kana. It really gives me the vibe that she functions as a reliable and emotionally grounding Kyotaro-type role within her band as well,
There doesn't seem to be any dispute that Momo is a ho, but apparently she's lovable enough to make it as her acquaintances' best worst girl. And to her credit, she didn't think Dai was still dating Sakura.