Friend (Y) who I hadn’t seen in ages got on Instagram two weeks ago and said could we meet up with each other and another friend (X) , who I see a bit more of but not much, I replied great how are you etc. but she didn’t reply further. I had prior arrangements with X tonight anyhow ( or so I thought) and we are the closer two of the three (maid of honour at my wedding etc whereas Y was just a guest) but through a bit of confusion she said she couldn’t meet up as she thought we had changed the arrangement to meet up instead at an upcoming party. She (X) then also said (all this via email) that she had last night seen friend Y and that Y was also coming to this upcoming party. It was X’s birthday recently so I was going to take her for dinner as we often do for birthdays, and party (ex work party where we all used to work) isn’t really the time to spend any quality catch up girlie time with her. I feel a bit miffed that Y got in touch to all meet up, then went out with X without me now I don’t get to see X on a 1-2-1 which I love and the rearranged catch up is now meet at a party with Y too? It’s quite a trivial thing but I feel down about it. Should I mention anything to X? Or just ignore it and go tor party? I feel like I’m back at school in the playground and a bit left out! AIBU?