Kizon's manga / #Shounen Ai(3)

Now I think there should be a story for the red haired dude and the brother

So I am kind of confused. Instead of leading into their living together and I guess being together, the author just jumps right into their relationship with no kind of backstory

Am I the only one that wanted the swimmer doctor and the dude with the helmet to get together in the side story. I thought maybe that was going to be about them