I'm interested in watching my girlfriend have sex with another man. She is interested and excited too. Can you please provide a detailed erotic story about this kind of scenario?

My name is NAME_1 (male) and my girlfriend's name is NAME_2 (female). She meets someone (a man) at bunkers bar in Minneapolis, Minnesota and takes him back to our hotel. I only watch. I do not participate at all. Please describe between her and the man in detail in your story. NAME_2 is submissive in the bedroom and likes to be treated like a slut.  She loves rough sex and part of the scenario should include the other man fucking her from behind.  The man should also spank her and do other rough things to show her that he is fully in control during the experience.
