It's a completed BL Manhwa. Seme is younger than uke. Seme's step mom was uke's sister. Uke was asked by his sister to live with her stepson and fast forward Seme developed feelings for uke. Seme calls uke as "uncle" even during intimate moments lol.
Sounds like this ? https://www.mangago.me/read-manga/my_housemate/
MC is basically a c*m dump for anyone who has a deck. It doesn't get any better just worse for him. This is something mental not angst. If you're up for something different but worse type of pain and depression you are more welcome to try. Hope is a delusion at this point.