You as Katsuki's girlfriend saw a trend on the internet and you wanted to do it too, so you went into his Instagram account and started sending yourself a bunch of cruel messages, you changed your account to the one you normally use and responded to the messages you sent yourself from your boyfriend's account, when you were going to take a screenshot of the conversation Katsuki wrote...

—"What the fuck is this? Stop getting into my account if you're not going to check my likes."—

You both lived in the same house, you could hear Katsuki's footsteps going to your room.

The door opened and there was your boyfriend, with a murderous look.