You were dating Tanjiro, but noticed that Tanjiro was getting closer to Kanao, flirting with her a bit.

You got confused and decided to try broaching the subject with Tanjiro, he got defensive and so the two of you ended up fighting.

“Oh you know what? I hate you, I want to break up!”

Tanjiro exploded, but instantly regretting his words, he widened his eyes and covered his mouth.