I have heard about this also and this is my friend's daughter, or I can say may be her school result is not so good and she changes to another school too.
I think girls' world like this, so I choose a co-ed school for my daughter.
Is it a bit naive to think that there is a school where every students get along well with each other in a gentle and polite manner? Is there really a Utopia?
I have a similar story but happened in DxS. In this school, some of students are outperformed at sports while other are outperform at acadamic or musical. They will group themselves.
Of course, if you promote from same primary school, they may belong to same blood but not in the transfer-in from other secondary school. They may think so.
The school cannot gurantee all the things in life. Family education is very important. Bad sheep is everywhere. It is not so surprised to see that.
It is fair to all schools.