12 years ago I worked in a difficult and pressured environment with a great bunch of people. We all bonded and keep in touch to this day. In particular I shared an office with two guys and we meet up every so often, follow each others careers and have a mutual Whatsapp group to chat about stuff among ourselves. During lockdown one became very ill and had to isolate even from his family; other friend and myself took it in turns with Zoom chats to cheer him up. Recently he held a dinner for a birthday and took the opportunity to thank various people, including the other guy, and made no mention of me. I feel enormously hurt by this. I have tried to brush it off, but simply cannot understand how he would have thought to thank this other guy and not mention me, when we were very much three together. It seems silly, but it makes me think I have been imagining a friendship all these years. AIBU?