How does one even get invited to parties where they don't know anyone?
I knew the hostess, and (kind of/only by knowing her) her boyfriend, but that was it. You do kind of have to know the host. More accurately, what I'd recommend is going to multiple parties hosted by the same person (despite not knowing/expecting to know anyone there). This is the second time I've gone to one of her parties despite - eek! - really not knowing anyone else there at all. It turned out 2 of the guests had been at the last party I went to, too, and everyone had been a sea of faces then so I didn't really remember them but it helped make an easier rapport. And by the end of the evening, we were all really clicking. So I guess, stick with it. I was really surprised.
Ah. Parties for me go one of three ways at this point, really. 1. I know the host(ess) and the majority of the people at the party. 2. I host the party. 3. I'm not at the party (as in, not invited/not in a situation like what you describe above). Not quite sure how to bridge that gap.
I met this friend through my sister, actually, and she was my sister's friend first. So I guess I would suggest going another rung further out in your social circle. You know, instead of hanging out with friends, hang out with friends of friends and kind of brachiating from there. It does sound like it's kind of a closed group though which is unfortunate. Can you develop new sets of friends via, for instance, work?
Work is a poor example but I get exactly where you're coming from. Most of co-workers are married/older/generally not people I want to see outside of work. Brachiating is a good visual.Can you develop new sets of friends via, for instance, work?