We'll see what Rio has to say when confronted, but I wouldn't be surprised if she blames Kyouko. Seems like there's some important unsolved grievances between the three suspects, quite possibly towards Mahoro too. Maybe each of them saw Rei-kun with an unrelated fourth girl, and decided to take...
I'm surprised Kaoru Mori has any trouble finding a magazine that would publish her manga... I thought she was a fairly well known and successful mangaka.
Hmm... That background group behind the commenter trio in page 4, I feel like I've seen them before... Though I can't remember what or who they remind me of. Eiji Masuda does like his references and cameos, but they don't look like any of his characters.
Or maybe I'm just thinking too much...
I don't know what the original japanese is like, but in this version of the chapter the start of page 6 can be understood a bit differently... I wonder if that's relevant at all.