Yaaas.
This is where the twist comes in. Q_Q (Too good to be true, that Ogawa Chise would make a sweet and normal couple for once lol)
So basically, you know how Kuzakabe almost stabbed the girl?
When Kuze hugged Kuzakabe, he realized that he wasn't himself before.
I'm guessing he's noticing that he's become a bit yandere, and that it was Kuze who manipulated him into loving to the point of almost injuring someone.
Basically, the mangaka revealed how twisted Kuze really is here, and that he manipulated Kuzakabe for a reason.
Tl;dr Kuze is fked up and Kuzakabe realized (づ￣ ³￣)づ
I think it's because Atsumi got scared by his own actions that he back away from Kuze. He doesn't know how to deal with all those possessive emotions. He tried to hurt that girl. He's starting to act violently like the others student were with him when he was the joker. So he's becoming what he is scared of.
I don't think he's able to realise the meaning of Kuze's creepy eyes.
Atsumu backed off, I think, because of Kuze's reaction. He almost STABBED a girl out of nothing but petty jealousy, and Kuze's only concern was Atsumu's love for him (when any normal person would be at the very least creeped out and suggesting that Atsumu get help). His reaction also helped Atsumu realize how terribly manipulative Kuze is, as well as how violently dependent he had become as a result.
So I suppose the ending dialogue (What do you really want?) was either Kuze or Kusakabe asking what he wanted: Would you rather have Kuze, or be alone with nothing and nobody for the second time in your life?
I was rereading the last chapter and something bugged me: kuza was hugging atsumi and was telling him that he is glad that atsumi loves him this much and then atsumi backed off from the hug. Why? And there was this creepy dark atmosphere and kuze's eyes and "what do you really want?"
Any suggestions about it?