it's not really overthinking
Even i as a reader suspected cuz they were some signs... remember when red haired and uke first met??in the elevator??seme suddenly become silent and was kind of in hurry when he saw the red-haired!! so i thought their might be some history between them and then when seme didn't call back or update uke anything that night he was waiting for seme and seme said he would go to his place but didn't?then the next day he saw them together!!and heard "thnks for the socks"!! and then uke heard the red-haired in upstairs talking bout the things that night and how he lent his socks to the guy he was interested in(that's when i knew it wasn't the seme he was talking abiut) it's understandable he was overthinking it lmao
What did I say? I knew red hair was interested in Uke, and that's why Seme told him to stay away. Seme and red hair didn't sleep together! Uke be overthinking things. That's why some people say, don't get into a relationship right away unless you have fixed your unresolved trauma.