私は彼女が彼女の新しいボーイフレンドと外出することと引き換えにお尻で私の義理の妹をファックします

My stepsister asks my permission to let her go see her boyfriend, I am jealous of her because she is the only one who can have sex with me, therefore I tell her that I will let her go out in exchange for her making me cum in her ass, which she agrees to and earns permission.