Diana blackmails her boyfriend into facesitting. She wants it and her boyfriend can choose - either he allows her to sit on his face or she'll end their relationship. That's her way of teaching him some manners and making him understand who's in charge in their relationship. Diana wants to use and humiliate her boyfriend - just like he deserves. And if he doesn't do what she demands she'll just dump him. But Diana knows that he'll do anything and she uses this advantage without any shame!