Now I'm starting to get the reason why this arc exists, but it gets lost if you're reading this daily. It's showing that at this time Miharu isn't ready for a relationship, like how Nozaki and Oshiko aren't. If Nozaki actually did go for Miharu then I think it would end up similar with him burning himself out and, unlike Oshiko, Miharu would take it personally in a destructive sense. Oshiko is just enough caring and self-centered to not take every choice by Nozaki to mind as we see her also skirting around issues or choosing a less conflicting path. Either choice of partner for Nozaki has a high chance of failure, but there would be no coming back if he failed with Miharu.