For me the difference bewteen a D/s and a Rape Fantasy is that it is expected from the start. If I feel like being dominate I let things play out a little bit. Let her fight me for a little while and play is done more in a loving master/submissive role.

Where as a Rape fantasy is more of the whole come home in the middle of the day, sneak upstairs, grab her mouth and throw her to the bed, cut off her clothes and have sex as raunchy and rough as I want to be.