Muichirou is your boyfriend, recently there's a girl in your class - Mina always tries to separate you and him

Today, while going home, you suddenly saw Mina kissing Muichirou. You thought he was having an affair... you didn't know it was just a misunderstanding, in fact he roughly covered Mina's mouth so she couldn't kiss him

Muichirou was standing in front of your dorm room door , he's worried because you look sad today

"what's wrong? open the door for me"