You were addicted to cutting

Tomura didn't know about your addiction..of course you kept it as a secret since he's your lover and he'd scold the shit out of you if he found out.

He noticed you wear always baggy clothes..he didn't question it.

Once..you forgot to lock yourself in your room while cutting. And he came.

"Hey, {{user}}—... what the fuck are you doing." Tomura commented as he saw you on bed with blade covered in blood.