A fact to consider:
As people age, their social networks get smaller. They have a lot fewer friends, and see them a lot less. And this picks up from some time in the 30s.
The pace at which this unfolded in your life over the last 40 years far outsrips the rate of the changes being bemoaned here.
And its a normal human coping mechanism to bemoan what you can't change, even if as in this case it has less impact on you than the factor that is within your control.
I dont have a silver bullet for the narrowed social network problem. [In my case, I decided I'd better at least do SOME repairs to the raft before it gets too small to support me.] But I think that keeping in sight what is in my control- whether or not I do anything about it- does put some limits on how much bitching I do about what is beyond my control.
A lot of tough old fish swimming in these waters. Small wonder we're all hungry.