I noticed as we get older, friends from the past tend to drift away and retreat into their own private and family lives. They often have problems of their own and concentrate on themselves.
I found membership at my local college pool for swimming laps really helped. Met a lot of other older swimmers and to share experiences with. A few have become causual friends. Also bike riding is a great alternative, and can meet other riders to chat about bikes, bike paths, and various destinations.
I think exercise and finding a physical yet fun activity changes one's perception as well as becomes a common interest that can help connect with others.