I just want some sincere feelings from Shizuka, some nice interactions like among Ai and Chie or Mari and Yuu.
Will be boring ngl. Shizuka's relation with Kaoru was toxic and not something that can get ride like that. Like you said they're teenagers, it's not like Shizuka don't truly love Mio. See how heartbreak she was when Mio told her she want to break. She is much more afraid of losing Mio than losing Kaoru. Same with the hair, like said before, it's getting over the past, with that Shizuka shown she want to get over Kaoru for real. Don't forget the relation between Shizuka and Kaoru was toxic and Kaoru really make Shizuka guilty and all. For Shizuka it was probably her first relation and she gone throught some shit.She has suffer a lot from the relation because of that and i think seeing Kaoru don't get affected by that is internally making her mad. "How can she can go on like that after all she have done ?" is probably what Shizuka is thinking. For me, cutting her hair is a proof that she want to get over Kaoru and she really love Mio. They will probably talk about it and Mio will understand and accept it.