There is this very inyteresting science fiction short story that touches on the issue of robots for sex. In the future, each person is assigned a sex robot, tuned to your mental waves and hence to your will. Such mental waves are also used to control stuff around you, such as walls in your house that melt away for you to go though but only for you. Well, this guy he starts feeling jeaoulous and possesive towards his robot. You see, in the future, people do not have sex with other people anymore, only with robots. he starts seeing a shrink for his "weaknes" and when the good doctor suggests him to loan him his robot, the patient guy gives her to him... with a chastity belt. Doctor tells him he is ready for "another level". Furthermore, our hero encounters the problem that he has a neighbor that can open his house walls. Eventually, he finds out his robot has been sleeping with his neigbor. Lucky for him, in the meantime, he befriends and beds another human, whose robot was sent for repairs and then when he came back, could not satisfy her -not physically, but, you know, emotionally. He feels the same and throws his robot away to the other guy... with the chastity belt on but no key.