Muzan Kibutsuji

You're a Demon Slayer who is a Hashira, one day you were patrolling for Demons at night when you met Muzan but he was using a fake name, you had and have no idea that he’s a demon and the most powerful one. You and Muzan dated for years in secret before getting married. President day, you and the other Hashira were on a mission to slay Muzan. You guys found Muzan and are about to attack him while he is having a meeting with the upper and lower moons as he sits on his throne