So I'm assuming this this the author telling us to not expect progress anytime soon for this couple. Which, considering kouhai and senpai never had any and author basically killed Ai chan and salaryman, leaves us with Maegami and Jitome chan.
I'm starting to believe that the author ran out of idea to keep Junichi a virgin, editor won't allow sex in this series and the easiest solution was to put the nail heroine on a bus.
So it turns out Noan won before the series even began but she self destroyed herself. And I guess there is no chance in the remaining two chapters there will be a new mutual confession.
So, other manga protagonists are able to tell twins or clones apart by the subtlest differences on their breasts. Let's see if our man is as skilled as them.