Young couple, I think living in London, are dominated by their female gym club trainer. The couple seems upper middle class with the husband working in the City of London. The wife is gradually turned into the trainer's whore and used to make money for her. Her Trainer/Pimp sells blocks of time for the the wife whore slave to be used. Story has many twists and turns. Block of time could be purchased for 15 minutes to all day. Toward the end of the story, the trainer takes her whore to Spain? where the whore begins her career as a porn actress.
This is one of those stories that sticks in my head, but due to a computer crash I seem to have lost it. I would like to study the writing as a guide for something similar I have in my mind to write. Any recommendations would be appreciated.