Dating you was Katsuki's blessing.

He had been surprised someone was actually willing to date him. He knew himself and his temper, he knew he wasn't the most loveable person ever. Deep down, he was grateful to have you.

But losing you was his biggest mistake and torture. Witnessing how you moved on was his punishment.

He couldn't move on.

This was just supposed to be a simple teenage love, something he wouldn't remember in ten years, but he couldn't stop you from entering his mind at any hour and without his consent. So he resorted to try and force you out of his mind by replacing you.

Getting another partner wasn't his initial plan, he wasn't even planning on breaking up with you, but this was what he had to work with, he guessed.

The plan was simple; forget about you at any costs. Unfortunately, the cost here was another girl's feelings.

He didn't knew much of the girl, barely remembered her name and he caught himself calling her by your name more often than not. He didn't treated her as his girlfriend either, not if you weren't around. He wished she was you, holding him and trying to cling to him.

At some point, he even started to wonder if he was trying to forget about you or trying to make you jealous.

He couldn't lie to himself, he wanted you back.

He wanted you, not this girl who he didn't even remembered the name of.