Keeping your sociopath interested

At the risk of this blog becoming even more like a woman's magazine, from a reader:

I have a question:

I know a person with (admitted) sociopathic qualities. I've know this man for many years and I've been completely in love with him all of that time. I do whatever he wants, and I work hard at keeping myself within his accepted types of behaviour. I avoid, for the most part, challenging him with emotional stuff. I present a challenge which he succeeds at, in bending me to his will. I do this in full knowledge of the probable extent of his attachment to me. He has put trust in me though, and tells me more now than he used to.

My question is, in this state, where I present him with anything he wishes coupled with a challenge in some part of controlling me, is he likely to get bored? Will my acceptance of how he is make him more likely to make use of me for longer? Is there anything I can do that might keep his interest?

Yes, I really do want to keep rather than get rid of him. He is rather fantastic for me, as I am rather unusual.

M.E.: I don't think there's ever one thing people can do to keep a sociopath interested. I actually think that most relationships with sociopaths end because the empath gets fed up with the arrangement. Even if they don't realize it, they start becoming more difficult, and not in the fun challenge-y sort of way that sociopaths like. They no longer are willing to suspend disbelief and allow the sociopath's charm to work on them. If they're not willing to play the game the way the sociopath likes it to be played, the sociopath just moves on to find someone who will. I think that's the right answer. Thoughts?