The thing to add with Pretty girls or girls who are pretty enough is that they don't need to chat you up. Some girls might chat a bit just to see what you are like or if they really think the world off you, if your a pretty boy who gets lots of girls, etc. However most pretty girls will get enough guys go to them so don't need to put in any effort there.
So if you're not chatting them up like the other guys do they will take it as you are not interested and/or are just not good socially/confident. So will lose interest and not want to bother once they have worked out you are not for them. So she has probably just lost interest and/or possibly a bit annoyed that you haven't pony'd on up like all the other guys to chat her up. Pretty girls are like that I think. They expect the poor guy to do it all 🙄