@Midoriha Except it's not socially unacceptable. That he's in a gathering of cosplayers complete with a guy in a drag being ironic is just the salt on the wound, not the wound itself. The annoyance is the MC's stagnant development over his own issue.
To everyone wondering about this people, they all appear in earlier chapters, the girls appear in the very first chapter and you can see them in chapter 5 again, even the drag guy appears in a panel of that chapter