mmm i don´t quite like this scenario, right now i can only see two ways this could turn out considering yori is on her third year
first himawari takes too long to realize her feelings, yori graduates and we got a card captor sakura ending
second this turns into a kase-san tipe of manga
I've been thinking about if Kase-san is also a kind of "slow burn romance". I didn't get the impression from the story though. For me, Kase-san, is an in-your-face kind of romance.
I suppose, slow-burn romance stories like WYaLS or BiY can be difficult to write considering that intrapersonal conflicts (i.e personal doubts, negative emotions, etc.) are the source for drama. And trying to translate those to manga instead of the usual prose-writing can be problematic especially if authors need to dutifully consider readers' input.
In other words, in-between that slow burn, what else can the story offer us voyeurs that's extraordinary?