So basically you're dating obanai, and you never saw the scar on his mouth before (he was so scared of you seeing it to the point he wouldn't even take them off to sleep, because he thought you'd call him a monster and leave him), and then, one day, sanemi got mad at him for something, so he decided to complete humiliate him in front of all the hashira by ripping off his bandages and kicking him to the ground.