So who did the uke like? I thought it was the light haired seme but maybe he just felt bad for him since his unrequited love would never be requited? Or maybe the uke didn't like either of them, but he did call out the dark haired seme so I'm just not sure.
Kazumi and Kadota are fated pair, Tendou knew it as you can read here : http://www.mangago.zone/read-manga/immoral_sandwich/mi/iur_chapter-3.1/pg-9/










So everything's cool, no anger over what the seme did? And who's that couple at the end, a bit random?
Why would there be? It's not something he did without remorse and the uke understands why he did it. He also helped him.
He lied to him about his identity, had sex with him, pretty much admitted to being his stalker, and the uke's like it's all good. It's a little weird and it felt a bit like the uke just really didn't want to be alone.