First post, although I've been a lurker for a while now.
I'll try to keep it short- DD is in year 3, in terms of her school friends there are a group of 4 of them who are particularly close, partly because the parents know each other well and they do things outside school together like brownies etc. DD and 3 friends have been at this school since reception as have most of the children, but a couple of new ones join in year 3 each year. One of the new girls as of September is in DD and friends' class, and has been playing with them a bit this term, but not all the time from what I can gather from DD- she says she plays with her once a week or so and sometimes she eats lunch with her. I'll call the new girl E.
So yesterday was the end of term, and when I went to pick DD up from school and she came out with her friends, it quickly became apparent that her 3 friends and two other girls in the class were going back to E's house for a birthday sleepover. One of DD's friend's mums was going to drive 3 of them there as they wouldn't all fit in E's mum's car. The mums of DD's friends, who I'm also quite friendly with, hadn't realised that DD hadn't known anything about it and wasn't invited- cue a very awkward couple of minutes before they all headed off home.
DD is understandably very upset she wasn't invited and yet her 3 best friends were, she did manage to hold it together in front of the other girls and mums but cried on the way home, very miserable today. Now I'm not angry as such, and definitely not at the mums of DD's friends, we've all gotten on very well for years and even if they did know DD wasn't invited, which I doubt, they couldn't exactly push for her to be invited to someone else's party. But AIBU to be sad for DD, and just a bit irritated at girl E's mum?