I so agree with you like "are you kidding me ". In alot of the mangas ive read the uke no matter what would stay true to his loved one Arggghhhh. If you gonna slap him can i have the first go? You know kinda like the opening cermony on its to a slap fest .
please, don't misjudge the uke. I was also quite angry when I saw the raws but once I read the spanish translation (my native language) I could even sympathize with his feelings. To sum up, he's trying to attain anything that makes him remember Aoi. The thing with his sempai is....well I explained to someone else in other comments but it's cause Nagatsuma "sees" Aoi inside his sempai, after a conversation where he tells him some things about Aoi. When he's doing it with the old geezer, 7 years had passed so obviously he got involved with other men, specially because he thought he would never see Aoi again, but afterall, he realizes that he never forgot him and that still he chases after his memories.
i hated the uke,he was so fustrating to understand.But i love the semi,and i felt sorry for him but that uke made me feel to slap him especially when he slept with another guy