Well. Fuck.
Ryouichi piecing the puzzle together, but he actually failed by forcing people:
1. Wakaba told everything, about bullying, being forced to confess and date Haruto, even if she would tell she does indeed love him, there's no proof, she might be lying to not get punished.
2. Since Ria was telling a lie by Wakaba being on it from the start and came up with the idea, she was covering for Ikumi, leader of the THOT trio and being punished by her. But he figured it might be also a lie, so he ain't that dumb.
I think it was a mistake by Ryouichi to force everyone to reveal the truth that way, poor detective work, reason for misunderstanding of the whole situation.
What's worse now, Haruto overhearing the whole thing and misunderstanding and not knowing the true feeling Wakaba shares for him because Ryouichi didn't let her explain.
Thanks for the scanlation!