I feel I am being a bit petty but not sure I am bothered tbh 
I went out with some other mum's from school a few weeks ago and one of them was G's mum - we were talking about the boys and G's mum said that G was best friends with another boy - who DS1 is always playing with and talking about. She also said that G talked about DS1 a lot and they seemed to be good friends too. I was a bit surprised as DS1 has never really mentioned G.
Anyway, I added G to DS1's birthday list (the invites haven't gone out yet) on the basis of this conversation - however, have found out through FB that G is having his birthday party today and obviously DS1 has not been invited.
I could do with trimming the guest list anyway due to £££ so AIBU to remove G off the list??