I was recently rereading I, Robot by Isaac Asimov and thought that it had potential for a number of scenarios involving the Three Laws of Robotics as well as the relations between robots and humans though in the context of these ideas the robot would look human, but the degree to which it is robot like I am leaving to my perspective partners for these ideas. These are going to be adult in nature but there is going to be more plot more than there is going to be sex, though sex is likely to happen.
Oh and for clarification,
Law 1, A robot may not injure a human being or, through inaction, allow a human being to come to harm.
Law 2, A robot must obey the orders given to it by human beings, except where such orders would conflict with the First Law.
Law 3, A robot must protect its own existence as long as such protection does not conflict with the First or Second Laws.
1- Terrance "Terry" Roland is a field tester for US Robotics and has a robot sent to Mars so that he can put it through its paces in the Mars colony. This robot is to be one of the first of its kind, in that it is designed to look, act, and seem human however it is still bound to the Three Laws that bind all robots so she will still fight under robotic regulations as set forth by the government. Terry's job is to see how seamlessly she can blend into society as compared to other robots, unlike them her positronic brain is created in such a way as to allow her to process, understand and feel emotion much as humans do which should further aid her in being accepted by the human kind that are around her.
Like any true field test, he is given a period of three months with the robot so that she could have a full breadth of testing in any number of human experiences and events. But the challenge is, can he not grow attached to a girl that he spends so much of his time with even though he knows that she is a robot made to make others believe she is human. And can she, a robot with emotions, not learn the most powerful one of all during her field test?
2 - Upon success of the US Robotics selling a new type of robot that is made to be human, a man loses his wife and seeing that he could customize the new type of robot that is being made by US Robotics decides to create the facsimile of his dead wife while at the same time wiping it from the record that his wife never died to see if living with some form of her that is given her general history and identity can be enough to quell the brokenness in his heart.
She would likely have to contend with the fact that she is truly a robot on the inside, even though she is fed to believing she is human, and likely there will be a conflict with the first law of robotics that she would have to find some way to reconcile should she become aware of her robotic nature.
So can you truly replace what you love or learn to love something else instead?
(More ideas are likely to come to me but those two are good for now)