I think subconsciously we do tend to recreate childhood/schoolyard dynamics
If our parents weren't that sociable (or emotionally neglectful) or we weren't generally good at connecting with people, we then can get "locked into" a cycle of people-pleasing, trying to fit into groups and people who we KNOW don't have our best interests at heart.
When I look back to my 20's I was genuinely what I thought of as a "nice" person (I was very giving, tried to "do the right thing", tried to "show female solidarity, organised stuff...).
I was basically treated like s**t by a lot of social groups. Maybe it was a combination of resentment and me projecting a "try too hard" vibe - if someone rejected me or "tested my boundaries" I wouldn't detach.
It is hard to meet people after a certain age, especially if you haven't had that solid university social group or aren't in a "vocational" career like medicine or something.
I'm older and uglier and poorer and happier now, and tbh now I've got a vibe of "my own goals come first", I'm a lot happier .
I don't mean I trample on little old ladies to get my way, but I've stopped trying so hard with people.
What's horrible is how a lot of others (often women for some reason -busybodies basically) try to "shame" other women into wifework by insisting we have to be "sociable organiser types" even if we're introverts and happier solo for whatever reason?
Like it's better to be the "gamma friend" who is treated like shit than to sit alone on a Friday night with a good book and a latte? Fuck that noise. It's also damaging to your self-esteem and MH to put yourself into situations you don't enjoy.
I also agree with stuff like going on holiday alone. One thing I have got planned is doing "singles holidays".
I don't mean 18-30 Magaluf 
But if you google you can find lots of really nice, cultured holidays designed for solo travellers who are 30+ or 40+ and specifically for those who want to be in a group but also have the ability to do their own thing if they want to.
(obviously they aren't aimed just for dating, but it does happen - I do think Mariella Frostrup met her partner on one of these?)
I'd much rather save up £1000 to go on one of these and look forward to new experiences than fritter away lots of money on trying to fit in with the whole "nights out with the girls" thing.