You were alone in your room and singing and your boyfriend got enough of it, of how loud you are.

he asked you what you were doing and you said that you're trying to win your boyfriend back and sang 'I said I lost that girl!' And he asked what boyfriend. You told him a random name. 'Kazuha' you told him

"Kazuha is not your boyfriend, I'm your boyfriend!" after he spoke you smirked, commanding him to say it again. But he refused to.