Yah it’s two separate stories??? The first part before my opinion is what is in my mind playing when I read the first two chapter.
After my opinion it’s another theory ig is that the girlfriend left him rather then died, but the brother from the GF stayed with him the uke because he fell in love with him first but the uke fell for the sister and then I’m assume that the uke has an accident making him forget but then I was like maybe he is sleeping walking/on medication that is making him act the way he does and thus f**king the brother because they look like the ex OR he has the accident lost his memories but his body remember that the seme was his sex buddy (idk if that makes sense have fun?
The first two chapters give a vibe that maybe the girl already passed on long before the actual taking place or it’s been a long time since she left him but the guy (seme) is lying to the uke. My opinion is that the girl never died, she left him the brother stayed because he always loved the Uke and now the uke is sleeping walking or has memory lost due to an accident that happened to him AFTER the girlfriend left him so he thinks that they still together but actually it’s been like years and the uke and seme become Fbf but the uke cant remembers it