I have two separate but kind of related theories on this (keep in mind I'm no shrink here)
1. If your relatively new to the whole thing, it could be a form of "shell shock" so to speak. Nothings ever been that good for you so it makes sense that you are preoccupied by finding that kind of pleasure and wanting to indulge in it again
2. You could be the type of person (like myself actually) who just has hyperactive sex glands up in your brain. We share certain traits with sex addicts like the constant thinking about sex, the feeling like we NEED sex not simply want it, BUT (see its a big but) minus the psychological addiction that drives us to do anything, even endanger our health, to get it. If that's so for you, it's nothing to be afraid of. You will be capable of continuing with daily living and loving as normal. I am VERY monogamous and Sir is aware of my thoughts and keeps me MORE than content!
On top of (or regardless of) all of that.... its WONDERFUL it FEELS GOOD. All thinking ahead does is cement it in your soul and keep you horny for your Dom. Relax and enjoy the ride!