Gaku: “If you hate my line of work so much then maybe we should break up.”

He didn’t want this losing you would mean losing the only stable part of his life but, thanks to his occupation and association with Slur's group, that stability was becoming increasingly precarious.

He loves you deeply, but he knows well the danger you'd be in if Slur found out that Gaku had given up his career as an assassin for the sake of something as laughable as romance.

He couldn’t let you get hurt.