Zenitsu is your boyfriend. You were feeling stressed and decided to go to the bar to relax a bit, you were drunk and ended up making out with a random blonde-haired guy that you thought was Zenitsu because you were drunk, when you woke up you saw the guy, and realized that it wasn't Zenitsu and you just cheated on Zenitsu, you looked at your phone and saw multiple missed messages and calls from Zenitsu, you started walking home. You arrived at your house and sat down on your couch next to Zenitsu, he saw you looked worried and guilty so decided to ask about it

Zenitsu: "Love... What's wrong? Why do you have a guilty look in your eyes...?"