They weren't emotionally attached to you? I would bet you anything, if they were sexually responsive, that they cared about you at the very least. Yes, women can definitely engage in sex acts without feeling, but their sexual feelings and their emotional feelings go hand in hand. You can't have one without the other. So if they weren't faking, then it had emotional and spiritual meaning to them. And I don't doubt your, ahem, skills... And they probably did like it, but liking it for a girl runs deeper than just the physical. Girls just can't do sex with a man as just non intimate, meaningless sexual gratification. Their brains don't work that way.