Okay hear me out: Terusatousai. Maybe even throw in Nendou too. As a treat.
Kusuo only really dislikes the idea of dating Teruhashi because of her persistence and the attention she draws, right? Well, what if Nendou and Satou effectively cancel out her Angel Aura™ and she starts worrying less about being the most perfect pretty girl? Kusuo starts finding her tolerable. Satou and Nendou are smitten with her, because she is God's Favorite and The Most Perfect Pretty Girl (it's science), and Kusuo is kind of warming up to her, too (now that she's letting herself act more like a person instead of method acting the personification of perfection).
Of course, Nensatousai are already together at this point. That hasn't deterred Teruhashi, though! She's still just as determined as ever to get Kusuo to fall for her. Only this time it's actually kind of working.
Anyway they eventually all get together. Sloppy makeouts are had by all, cuddle piles are shared, truckloads of coffee jelly are eaten, etc etc. Happy ending.
