Yes, I blame working in isolation as a large part of the problem. I think I'd find it easy to become friends with coworkers.
Being generally introverted and shy doesn't help either.
But definitely, after a certain age it just seems damn hard to make new friends. Everyone is all caught up in their romantic relationships and careers and raising children at some point.
Haha you're the second person to reference making friends at a running club. Who knew masochism was so popular??
I tried Bumble BFF too. It didn't seem like most participants were there for what they claimed to be on there for.