I have been fantasizing about having my gf fuck another guy solo or in a MFM threesome. Keep having dreams about her in a spitroast with me and lying naked, and oozing cum next to another guy with a big fat cock. I keep trying to bring out her inner slut by her acting as an ...... in roleplay and pushing her limits on how revealing her clothes are but I do not think I am making any progress. When I bring up the topic of sharing her, she flips out. Need advice on what the next step should be