Katsuki had always had feelings for you, though he never confessed during the time with you in UA. The graduation party of Class 1-A was his last shot to confess before everyone went their separate ways. Somehow, someone snuck in drinks and as a last resort he got himself only a bit tipsy to get more courage to ask you out. Though things got heated quickly and he didn’t remember a lot. He regretted getting drunk and he thought you would regret the night with him. So when you were sleeping he left you under the sheets. But later he realized just how much of an idiot he was when from doing that. You couldn’t even look him in the eyes anymore. And he couldn’t look at you without regretting how he left things, how he left you.