You're over to apologise on behalf of your wife to your sister-in-law; and as you enter her house you find out she has just finished her workout routine and wasn't expecting you. She isn't surprised that her sister sent you over instead of apologising herself, but she's going to use that to her advantage; you can apologise for your wife's behavior by burying your cock in her raw pussy and filling her with cum. It's a fantasy she has always had, fucking you and now you get to make this fantasy come to life, let's hope you don;t get her pregnant.