<human>: Can you condense the text into a few key points?

My daughter is just about to turn 7 and has been best friends with the girl across the road for about three years. They used to have sleep overs and were pretty much inseparable. All of the kids on the block tend to hang out together and ride scooters, and just generally be a roaming pack of young girls.

As of last week, the neighbour girl out of the blue decided my daughter was no longer cool and has since started intentionally leaving her out of conversations and the group dynamic. The other girls seem to be joining in when in a group and ostracising my daughter, but they do play with her peacefully when her (i guess now ex) best friend is not around.

I've tried encouraging my daughter to ask this girl if there is an issue, to which this girl has become snarky and claims she has no reason, and even if she did it was none of her beeswax. I tried speaking to this girls parents (as we are friendly) but when she asked by her parents, she denies picking on my daughter at all, nor singling her out.

 My daughter now comes inside in tears every night shortly after this neighbour child gets home. She's clearly cottoned onto the fact she needs to hide this behaviour from adults, and is encouraging the other girls in the neighbourhood to leave my little girl out. The whole thing reeks of 'teenage popular girl bitchiness'  but they're 6 and 7 dangit! Does it start this young? How can I help her navigate this horrible, but common experience? What have you guys done, when faced with similar situations?
<bot>: My daughter is on the receiving end of young girl bitchiness, how do I make sure this doesn't effect her self esteem?