Well, I've never had trouble making friends, I'm pretty social, but it seems like a lot of people my age are still bound up in their (almost grown/grown) kids' lives, spend all of their time with family/relatives, or just aren't into letting new people into their lives. Some of this is New England, heck, I'm a native, and I know we are not a particularly friendly bunch! Living in the west cured me of that, but even though I never, never regret the choice I made to come back here, we have never developed the group of friends like the ones I had in Tempe. I know lots and lots of people and have had various friends here over the years, but most have faded away, as the interests that brought us together were no longer relevant for me.
On Wednesday, I am going to the last ride/event of the group I have ridden with for 6-7 years. They are a unique group, mostly older than me. I haven't been to one ride this season. When I had the time, I didn't want to drive far to a ride, and I chose to ride with Hirakukibou, who is a friend I made through TE! And sometimes work interferes, although I sought a less than full the job on purpose, so I could continue riding with this group. I keep Wednesdays clear, except for one client in the late afternoon. But really, I haven't developed a friendship with anyone in this group. They are nice, but most have known each other for many years. Even in the past, I didn't ride with them every week.
Another thing is, I stopped being socially friendly with people from work, quite awhile ago. That used to be a big part of my life at one point. And now, my colleagues are mostly closer to the age of my kids.