Your GF is either very needy, very insecure, lacks confidence or very much in love. BUT, too much of a good thing can get sickening. Many say how lucky you are. I wonder how many of them have had that experience. After a while it gets exhausting and you start to feel smothered. Is she trying to validate her relationship to herself or to you? As far as thanking you for things you do, that's no biggie. But as this situation continues to annoy you, you will find other things that annoy you until the relationship ends.
I don't think you are cold, hard, or lacking. Just someone who doesn't like to be smothered. I could never stand being around someone that has to "express" themself to me 24/7 or with someone who feels that they need to constantly validate the relationship. Independent women don't generally translate to independant secure emotions. It seems that it she continues she is only going to end up pushing you out the door. Did you tell her that she is doing the very same thing that caused your other relationship to end? Have you asked her if she feels secure in the relationship? Clearly if you can't accept her love the way she expresses it - which doesn't make you the bad guy - you both need to find someone who compliments the level of the needs you each have.
I don't think you should have suck it up or learn to appreciate it or live with it, nor should she stop if that is her nature. It just means that you two are at opposite ends in that regard.