My ex-girlfriend wanted an open relationship (the truth was, she had an interest in her personal trainer (male) at a gym. I suspected that this was the case, yet amazingly, the gym seemed to be okay about these sorts of things! If I had been the manager, I would have said to them, "Rule Number One, Professional Detachment. Your role is to train the client, not to be their friend, or their lover. ) which was repugnant to me. Had I agreed to it, I would have done so for the wrong reasons.