DS1 graduated this weekend, at the other end of the UK. 8 of us went down, including my DM, DH, DS2 & 3, other family members, and stayed over the night before the ceremony. DS1's girlfriend came on the train in the morning. After the graduation ceremony, there was a formal lunch for DS1 and a maximum of 2 guests. DS1 said that he wanted his girlfriend at the lunch, which left 1 other ticket. So we decided that DS2 would be the other guest. The rest of us would go and have lunch elsewhere and meet up afterwards.
My DM is now rumbling away, saying that the GF should not have gone to the formal lunch, that it should have been me and DH instead, as DS1 "Has only been with her for a year" BTW they are now living together, moved in about a month and a half ago.
AIBU to say butt out, she is his partner, we don't mind, (It never occourred to us to mind) and that having his partner at the lunch was what DS1 wanted at his graduation!