First of all, we have to understand what emotion really is. We can program the robots so that a robot pretended (like humans) as if he is missing someone/something. We can give it mimics, crying face, even tears coming from its eyes. But it doesn't mean that it is missing that person/thing like humans. It doesn't mean it is feeling that PAIN of missing. The tears in our eyes comes out because of that feeling of MISSING/SADNESS, but for the robot it is because of the algorithm that, for instance, commands the robot that if someone/something is far away from you, make these mimics and bring water to the eyes etc. This is not the feeling of MISSING as we clearly know..