Airflyingfairy it's good to offload and you aren't stupid. These social problems can bedevil us and let's face it, most of our problems are '1st world', but that's the world we are fortunate enough to inhabit.
I do deplore the tendency of some people on this site to put others down and trivialise their concerns. Surely mutual support is better?
Most parties have a start time and you sort of arrive any time afterwards, so I would say if start is 7.30, latest arrival (without prior explanation) is 8.15ish. Buffet opens about 8 and there is PLENTY. Parties are supposed to be relaxed - at least, that's how I've always thought of it
I think your friend is a poor hostess, that's all. If it had been my party I would have been continually scanning the room to make sure all was well (which is probably why I hate giving parties and have NEVER had a birthday party!)
The rudest experience I had was when going with my partner to a friend's house for supper. My 'best' friend also came, with her husband, so there were six of us at the table. The hostess and my then best friend (bit of a silly notion, but there...) got deep into conversation about things they were both into - local choirs and culture - none of which I was involved in, or knew a thing about. The host talked to my friend's husband about their shared interests - not as exclusively as the other two women but enough to make my partner feel left out. We almost literally said nothing but 'please' 'thank you' and 'lovely' for about two hours. The following day I felt so low - stupid, confused and put down.
When I'm giving a supper party I'm always aware of how others are feeling and whether everyone is included, as much as possible, but I'm still not sure if our hosts were blind and indifferent, or just thought we were dull, boring and not worth bothering with. (By the way, I'm not really stupid. I have an MA, I'm a writer and counsellor, and I've written many books and I have plenty to say on certain subjects!)
Since then I've not bothered with the hosts, except for a thank-you note, and I see much less of the woman I thought of as the friend closest to me.
Your friend was possibly overwhelmed and just didn't think (or maybe had a tad too much Prosecco!). That's life - we have to harden up and shrug it off!