When I retired, I thought it would be as easy making new friends in my older years as it had been in my younger ones. Unfortunately, six months prior to my retirement, my second best friend died and six months after my very best friend died. It did leave me bereft and feeling alone.
I did charity work, joined different local groups, etc. However, although I made lots of aquaintences, none of them became friends.
Do think that friendship is based on common, shared experiences.
Still have one friend from old times fairly nearbye, but do not like to see her too often and wear out our friendship. My SiL, with whom I was also very close moved far away last year and although I can now go and spend a few days with her every so often, it is not the same as having someone I could just drop into for a cup of coffee and a chat.
I do feel pretty friendless these days, but have to accept it is part of the price of going older.