Surprising development. I think it works here but it failed in Nisekoi because that story did the switch in the last five chapters, which in that two hundred trirty chapter story meant it happened right at the end. Here there are a full ten to fifteen chapters and we already got to see the main leads date (and for him to realize he doesn't actually like her). The hives seem to be some insecurity but can also be seen as his feelings if rejection bubbling up when he feels overwhelmed.