I'm just now seeing this. Do you suppose that she feels like she tried it, got a good idea of what it was really like and it just didn't have enough appeal for her. Could it have anything to do with the personalities of the guys she has hooked up with? Maybe they have influenced her by being "too much of this or not enough of that". It could be that she sees you as the most compatible partner and the sex with the other guys isn't exciting enough for her to work past their idiosyncracys.
Does the topic ever come up in or out of the bedroom? If she never initiates ANY discussion about it then she inwardly wants it left alone, she's not going to feed the fire. The seed is still there. If she wants it (and she knows she can have it), she'll bring it up. There's also the good chance that in her mind the net result carries more negative than positive now that she has true experience to draw from.
