especially in a place like Japan and in high school specifically where you're judged for literally everything.
I forget exactly where I first saw it in a manga (it might have been
Girlfriends by Milk Morinaga) but the idea is that close female relationships, even ones that turn romantic, are just considered a "phase" that girls will grow out of which has some...unfortunate implications and frequently causes issues with stunted social development when genuinely homosexual people are told their feelings are just a passing fancy that they'll learn to ignore/deny once they mature.
It's a bizarre situation where they seemingly are accepting of that type of behavior but only because they don't treat it with the seriousness that it really deserves. Hina's behavior with Mahiro reminds me of this. To her glomping onto Mahiro's arm and telling her pick the eyelash off of her face (things you'd typically do with a lover) is just a "close female friendship" and is perfectly normal.
Similar thing with Asahi and how he treats Kaede, to him it's just a "close male friendship" but really when you think about it would you really "tease" your homie by pinching their cheeks like that? Kaede just accepts it because it's how Asahi has always behaved but I don't believe we've ever seen Kaede or Izumi behave that way towards Asahi so at what point do you stop and go "Hmm, maybe Asahi has a thing for dudes too?" and that exact disconnect is why Asahi is confused on how he really feels about Kanefumi. Asahi has always thought (and been told) that that sort of closeness among boys is "normal" but he's taken that for granted and the dichotomy becomes readily apparent when he does similar things to a guy who actually likes him in that way.