My experience has been similar.
There is a lot of 'asking each other out' it seems as if the boys are in charge, they like to 'reject' the girls or go out with them and then break up in front of their mates to humiliate her. They go out with one girl and then her best friend the very next day splitting friendships.
I can't understand why these girls allow themselves to be used like this it's really depressing.
My DD has shown me the type of selfies the girls post on instagram and snapchat. Provocative 'mirror selfies' in their underwear, pouty selfies wearing make-up and using filters. With hundreds of people liking them and commenting, they 'tag' boys in the photo to get their attention and then get comments. Girls with the most comments and likes are hated by other girls, bickering also starts amongst the girls when someone's boyfriend comments on another girls photos. Again causing trouble between friends.
My DD is pretty and clever and kind, quite shy. She doesn't post selfies or chase after boys, although has silent crushes from
Time to time. She feels as if there is something wrong with her as she is overlooked by the boys who find her boring.
We have had some very long talks where I have tried to show her that not all boys are like this, there are quieter more sensitive boys out there who don't try to bring the girls down, and with age they will mature (as will she) and she will find herself a real boyfriend when she is old enough and ready.
She feels very low at times, there is a lot of low key 'negging' going on, it really depresses me and I feel like I am constantly lifting her up after a day at school of not feeling good enough.
I wish these girls would stick together, stop competing and lift each other up instead of letting silly boys attention make them turn on each other.