#probably also wrong

since rereading it again, I'm completely flipped what my headcanon for their history is.

I think that Seiji was the oblivious one, and Jesse was actively pursuing him without Seiji realizing it.

I thought "what event could've thrown Seiji so much for his match with Jesse?" My thought was either Jesse confessed to him, or kissed him.

And then Seiji running away after the loss also makes perfect sense. He would've felt a sense of betrayal that he and Jesse viewed their relationship differently.