Tell me about it--74 and have same issues--although grandkids who live near me are adults they are same and my adult kids ? ppphhffft
Friends from long ago either deceased or 1/2 a couple & seem afraid to do anything without their "other"

I find gardening helps --a pet if you like an animal & dont travel much--and the old adage--volunteer where there are chatty people.
No one knows you are alone --its hard to start but only cure is to make yourself go where people are --talk to strangers ( in safe places)
Good Luck xxx
i'm in australia-same worldwide