I have a dd1 in Yr2 who's going through a difficult time at school. She has a best friend who now has found another best friend aswell & dd1 feel pushed out. There are times when there is teasing from the other two & then they are the best of friends again. Just before half term, I found out that if she wasn't allowed to join in a game, then she would go & hide in the toilets!!
I have spoken to her teacher who was extremely empathetic & is covering relationships in circle time in class & monitoring the situation.
I try to explain that it is good to have lots of friend & not just one friend. DD1 gets very upset. I know whilst I try to support her at home, this is something she will have to try & learn for herself in the playground.