Trying to find something I read

I'm pretty sure it begin with the MC trying to screw another female student but his step-sister? keeps interfering. The step sister was devoid of most emotion and she kept a straight face. She interfered by knocking on the door and asking if the MC needed a condom. Eventually he gets pissed off and tries to intimidate her but she ends up embarrassing him. It's revealed that the step sister aspires to be the MC's wife because the MC complemented her cooking? or something related to house choirs. I think the step-sister wore a headband.

Thank you.