My boy thinks he owns me or I am his toy. I have no idea what I did "wrong" either, Rachel. I don't spoil him to the point of making him think that..that I know of. He knows he has to obey commands to get food and such. However, I know he thinks I'm his toy or "his" because we'll be sitting and he'll put his paw up on my arm. I make him stop all the time, but he still does it.
After 3 and half years, I decided he must be right - I'm his.
He doesn't have separation anxiety, though. So the two are not related - or at least, they are mutually exclusive.