No, that wasn't what I was saying - I also don't have an issue with DH going abroad, which I've said repeatedly. And I've also said I think a cohabiting/LTR has as much value, and that I think they should be asked too.
What I was saying, was that:
a) I was talking about people who haven't felt the need to get married at all (unsurprisingly) not seeming to have the same attitudes as those who are married - ie not that people who would let their DH go don't have the same values as me/don't value their marriages as much (since I've said I would let my DH go too how can I be saying that?)
b) people keep conflating the two things - whether it's OK for her to feel annoyed at not being asked, and whether it's OK for her DH to go (he is going)
I think the whole thing about whether the DH should go is a red herring anyway. It's not what the thread was about. OP was asking whether she was U to be annoyed she wasn't asked, not whether she was U to let him go.
OP: goodness that's extraordinary that she hasn't invited me when we've been together 20 years. Surely that can't be normal these days. I'm off to ask Mumsnet: "AIBU to be annoyed not to be invited - has social convention really changed?"
Mumsnet:
Lots of married people: "YANBU, I'd be annoyed too, I think it's rude, though I would/wouldn't mind my DH going and yes it can be quite normal these days"
Lots of unmarried people: "YABU, I wouldn't mind if my DP weren't invited, lots of people don't invite partners, that's quite normal these days"
OP: (hmm yes lots of people say it's normal these days after all, better suck it up) "Ah, OK. DH is going."
Me: "Gosh, isn't that interesting. Lots of the married people are saying it's rude. Lots of the unmarried people are saying it's OK. It must be something to do with attitudes to marriage. Personally I'm a fuddy duddy traditionalist, and that's why I feel how I do about it, so maybe that has something to do with it."
Anyway, the OP has her answer now - lots of people do think it's OK, and it is increasingly normal after all.