Unmei sugite Tsugaemasen

Nagina, an Omega, finds himself in a dramatic reunion with his Alpha ex-boyfriend and ‘fated pair’, Sora, when he moves into a new house. Nagina has repeatedly gone out with Sora and broken up with him. He has dumped him right before they have sex. Thanks to that, Sora seems to bear a grudge against him to the point that he’s even planning to take revenge. But it seems like Nagina has a deeper reason that prevents him from becoming Sora’s pair...