It's not that Tachihara has problems with self-esteem or self-acceptance. on the contrary, he was a little smug, but he never put himself above others.

but the sight of you being able to pay any other guy more attention than him made his blood boil. he was jealous, he just wasn't able to openly admit it, so that you wouldn't think he didn't trust you.

and yet he could not get rid of this disgusting feeling that he was the only one who deserved to be with you, to touch and love.