To be hurt I’m not invited to the whole of my friend’s 50th?

Is she paying for everyone?

I would be really hurt by this.

The big difference is that your DH isn’t coming and so perhaps she was hoping that the DHs would watch the kids on the Friday so that the ladies can go off and do their own thing - but surely you’d just say that.

Are you sure that its definitely just you who has been left out? Maybe message and ask her- Are [names of all the rest of friendship group] all attending Friday and it's just me not invited to that part? This would serve the dual purpose of checking what's happening and pointing out the unkindness of the situation

That's far too passive. It sounds desperate.

I wouldn't go to any of it.

I'm guessing the birthday lady isn't just inviting this group of friends but lots of friends and family, so with every group within that, she doesn't have to invite everyone e.g. everyone from work, everyone from school, everyone from back home, everyone from this group etc. Plus OP says they're all bringing their families. So no, it's more like the difference between say 20 on the friday night, or 50 if she had to invite everyone from each group represented. While this friendship group of 6 is how the OP know the birthday woman, it's not her only or main friendship group and the OP isn't close to her within it, so in that context, it's not such a big snub and just her genuinely trying to have one quieter night with the people she's closer too before the big party on Saturday. I think it's fine and would try not to overthink esp as OP knows she's not that close to her.

I don't get why she's trying to keep the numbers low at a glamping/camping party? Presumably you're all paying for yourselves. If it's about there not being enough room / tents, it seems odd you can go one night and not the other. Is it a really big party or just the 6 of you? If it's just the 6, it does look off. I'd be fed up OP.

‘Hi friend, I understand the need to manage numbers and fully understand why you are arranging things like this. No problem at all! However I find whenever I attend part of a celebration (eg. The evening part only of a wedding) I find there is a vibe where others there earlier bond somehow and I always feel awkward and don’t enjoy it when I come later. For that reason, I’ll pass on the Saturday. Thanks very much for the invite though and I do genuinely appreciate it. I hope you understand and really hope you have a great time’

If I’m not good enough for Friday then I’m not good enough for Saturday.

"Ok friend, I understand. I think though, I'll bow out of the whole weekend, it would be a bit too embarrassing and awkward arriving on the Saturday when the rest of the crowd has been there since Friday. Don't want my kids to feel awkward either"

I wouldn't send a card or gift.

I'd say "nah, CBA doing ony one night" and leave it at that.

I think this can be the issue with larger groups .
people will have closer ties to some people than others

Yes, this is how I would feel ….although you may cut your nose off to spite your face

Are they other friends bringing children?

Could it be Friday is adults only?

Is it the children? How old are your children compared to the other children going on the Friday night?

I love this

you are 100% right in everything you said.

This is really odd and I’d be hurt too.
What is the friendship history? We’re you a later addition to the group, so for example the others have known her from school / uni so your friendship isn’t as established?

Many years ago DH and I weren’t invited to the whole day of a friend’s wedding, only the reception. I was initially a bit put out as we were a close group, they’d been to ours the year before. The venue was small (registry office) so more limited than we had been. But when I thought about the friendship dynamics, i had originally met here through one of the other friends in the group who had known her for a lot longer. We saw them a lot as we all lived closed together and could easily hang out every weekend. I realised that she wasn’t shunning us, it was just practicalities.
im not saying this is the same for you, just giving a different way of looking at it.
if I was you, I’d definitely be pissed off.

I seem contrary to other uptrhread but this stood out.

I get that she and I aren’t as close as some of the relationships in the group.

i think just ok to have a group and get in better with some people in it than others. There are some things that have capacity limits and it seems like the Saturday is the bigger night in this situation. Don’t look for the slight that she prefers others to you for the more intimate Friday. Look for the positive that she wants you there in the Saturday.

If you want to get closer work in the friendship with her for next time?! Don’t do what others have umsuggested and not go to the Saturday. That’s just incredibly petty and she will be happy not to have a friend like that there. It sounds like she’s tried to handle it sensitively

I wouldn't go at all.

Are all the others from your group of six definitely going on the Friday night? If so, I would be dreadfully hurt.

To just exclude one person out of 5 is pointed and hurtful.

i wouldn’t go to any of her event and I’d be reconsidering this group.