Ore To Joushi No Kakushikoto
A selfish boss and his subordinate end up in a hotel because the trains have stopped running. The boss, too drunk to recognize his coworker, comes onto him and asks his subordinate to film the encounter, giving him the perfect weapon for revenge. Only the more they get to really properly know one another, little by little, their relationship begins to change. I almost skipped this and am so happy I didn't. This was a fantastic love story, well paced and believable. I agree with other commenters who said this has the best confession scene they've ever read!
Attack on Titan dj - Others' Husbands
Years after Erwin leaves him, Levi finds them neighbors and they begin an affair.
Kono Ore Ga Omae Nanka Suki Na Wakenai
When the boy who rejected him in middle school joins their class - and worse, doesn't even remember him - Fujima decides to make him fall in love and reject him as payback. But then he remembers why he loved him in the first place.
Tsukiatte Agete mo Ii n Dakara ne