In general I think the relationships tend to be more one-sided because the member sees so much more of the model. They see us live, in our homes, etc while we see them primarily as text on a screen. In general I think that makes it more likely for the member to develop feelings or an obsession than the model. Same principle as fans vs celebrities, just because we see and can form attachments to people who don't have the same interaction back, maybe?
I still don't blame members for wanting to keep their info private; I think everyone should. But even in this forum we've seen multiple models being stalked by members and I don't think I've ever heard of the opposite.