My DD 11 was not invited to one of her best friend's party at the weekend. It sounds like it was a sleepover with just a small number of people. Friend has just moved to a different secondary school so invited one or two from her new school plus two girls (also DD's best friends) from her old primary. DD was quite close to this girl - spent quite a lot of time with her in the summer etc. DD whatsapped the birthday girl to ask why and she replied 'if you don't know then that's why' leaving DD hurt and confused.
I have my whole life often felt excluded from things, and don't want her to feel like that (although I know this is not the first time this has happened). I told her sadly friends can be very mean but to know that she is better than that - she'd never do that to a good friend. Do I get involved and speak to the Mum or would that make it all worse?