This is a display of human evolution in action. There is nothing wrong with what she's doing in a rational sense - unless of course the blatant use of sex as power throughout the media is something that is also worthy of such a stir.
My only concern is a lack of communication between you two. If he really doesn't know about how you truely feel, something deep and essential is missing in the relationship. If you're not communicating your desires most likely your relationship is bound to fail. & I wouldn't be concerned about sacrificing your position; Chances are he either enjoys or needs what it is the relationship gives him.
In addition, I have to wonder if you actually *love* him...? I've a more dominant personality myself and in my past relationships I've been told that I was often in disregard to my partners' feelings. I was unaware of this at the time, but I'm sometimes considered a coldhearted bitch. *Snickers*
I can identify with what it is you're doing but honestly the little mister ought to know a thing or two about who you truely are, because when you've got a man by his thang, you've power equivalent to the fire that burns within him. For the psychological (and possibly even physical) health of both of you, you are wise to express your true nature to him A.S.A.P. and that means very relatively soon. I have to wonder how long you two have been seeing one another... ???