I wrote this once before, but it didn't seem to post. Not sure this will be a popular take, but:
Until this point, I'd been pretty sure that Ayako was aware of Akira's feelings for her and was fencing them away, but she seems genuinely flat-footed here. From what we've been shown Akira's clearly been in love with Ayako for years. Akira picked up on that early, that's why she sees her as a rival/threat. I definitely feel like this is a last-ditch play to see if she has a shot, rather than just her "playing cupid".
I was a bit surprised by Akira's frankness and honesty on the incest issue. Regardless of where you actually fall on the issue itself, it would be pretty socially acceptable for her to play up the negative stigma around incest to push Ayako away from her rival, but even though it would definitely improve her chances, she doesn't do that. There's an actual principle there, and it's pretty admirable in that sense. It makes me like her even more than I already did, and kinda makes me sad that Akira x Ayako almost certainly is not the end point for this series.
I honestly ship them a lot more than the main couple. There's a troublesome power dynamic between Ayako and Asuka, even without the incest angle. Adult woman x small girl-child is seriously troublesome to begin with, the incest just makes it worse. There are legal and moral issues all over the place. We have statutory laws for a -reason-. It's at least somewhat better that Asuka is the aggressor, but that just makes it less bad, not okay..
Ayako and Akira could have a happy, healthy relationship and Asuka would get over her broken heart in time. But I'd be pretty surprised if this went that direction. But eh, I can enjoy a thing in fiction without being okay with it in real life.