Honestly, the most unrealistic thing in this series is the fact that Aki felt in love with Yori instead of Shiho. I wonder what kind of thought process went through her head to make that happen.
Well, Aki instantly fell in love with Yori's singing, but I think Aki's dynamic was also a bit different with Shiho from the start. Yori has a shy and awkward side, but isn't particularly troubled, so Aki could idolize her for her voice with not much getting in the way of this infatuation.
On the other hand Shiho carried deeper vulnerabilities, and didn't hide them very well, so Aki was compelled to take her under her wing, instead of idolizing her. The vibe I get is that Aki used to regard Shiho akin to a little sister she wanted to take care of, and only started seeing her in a different light when Shiho confessed to her, post-fallout.
Though Aki already has a real little sister, of course I don't mean that she saw Shiho as a literal blood relative. Rather that the feelings she has held for Shiho have an oddly gentle and warm foundation, which we could just call platonic, but feel kind of intense for the relatively short time they were close friends. (Compare the old school Yuri trope of sisterly relationships between senpai and kouhai, aka Class S culture.)
Some people seem to want to pathologize the way Aki is so quick to suggest taking the plunge with dating, calling it a desperate attempt at keeping Shiho close. But notice how Aki is not very isolated, and has a number of friends looking out for her. If Aki is desperate, then it's because she regrets letting her go back then, and doesn't want to repeat that mistake. Isn't there more than just desperation here? Rather than just keeping Shiho around as a friend, Aki seems to almost yearn for Shiho's presence. Even after their fallout, she never truly hated Shiho, and never stopped missing her.
I'm not saying that Aki has always been in love with Shiho, but she has always held deep feelings of some kind. Though her thoughts in these latest chapters have been left mostly unstated, it's pretty clear to me that by now an attraction has mixed into those feelings. Just look at her face when she was going in for a kiss. None of those thoughts are in the Bible.
I guess this was a long winded way of saying that some things needed to change to enable Aki to see her on again of again bestie in a different light.
This was interesting. Enjoyed hearing your thoughts. They're in line with some of my own, especially regarding their current relationship. Looking forward to more development from the leading couples, AkiShiho and YoriHima.