Dd is 7/y2. She had various friends in rec/y1, including one sort of on/off "best friend" - they waxed and waned in what seemed to be a healthy way and also often played with various other girls, but did always seem to gravitate back to each other. DD seems to me to be a completely normal kid gets on great with her brother and cousins and makes friends easily outside school eg on holiday club.
In y2 suddenly it seems like the whole class is in one tight exclusive pair or group or other. The "best friend" swiftly dropped DD for a new girl. I advised DD to not go chasing after them, especially if they were not kind to her "you can't play" and the like. Encouraged her to play with others, had a few play dates to help her broaden out etc.
It hasn't worked. Seemingly all the girls are in very tight 2s/3s, DD is a perpetual unwelcome third wheel asking to play. No ones invited her for play dates back. I keep calmly cheerfully saying "don't worry just find someone else to play", but everyone keeps saying you can't make kids include others etc, what the fuck do you do if no one lets you play? Her big brother has said she's ending up on her own a lot and joining him (he's kind and is fine with this). He also told me quietly he's seen former "best friend" running away from her when she asks to join in.
She was completely fine till now. Confident, sociable. Why are little girls so mean to each other?
I just don't know what to do. Asked teacher, who shuffled tables around at one point but can't do much else. Poor DD is just getting sad and her confidence is drifting away.