Sounds like she wants to be married but lead the life of a single party girl...cake-eater.
Does she work?
Devil's advocate here:
First, let me say that going to a singles meetup is a no-no, duh. But to be fair, that particular group was previously listed as a singles meetup, then changed to a 'professionals' meetup. It is entirely possible that she is/was naïve enough to think that it would be strictly professional (despite being at D&B...
Anyway, how do we know that OP wasn't invited? Not just to that particular one?
I'm almost 40. I meet people the old fashioned way (by yelling at them to get off my lawn). People under 30 do things differently, like meet new people online. For the most part, the under 30 crowd has grown up with the online world, and pretty much everything is done that way. Meeting new people isn't any different, but it's a concept that is relatively foreign to those of us at a certain age or higher. By the time the internet caught fire, I was already in my early 20's, and very few people had cell phones. Texting didn't exist, online dating didn't exist, no facebook, no camera phones, etc.
So, boundaries need to be discussed, obviously. That's a given.
But on the other side of things, this is how things are done nowadays. We have a new wife, in a new city, possibly with a husband that has no interest in meeting new people, helping his wife meet new people, or even going out socially.
There are better ways to do this on her part, but is she expected to sit at home and not be social? Is she expected to just be friends with the people her husband expects her to be friends with (ie. his friends and their wives)?
But agreed, absolutely, her choice of meetup groups needs to be revised to those that are marriage-friendly.
I blame age and a generational gap for this. Also lack of boundaries.
Also, what on earth is stopping him from going along with her?