Since I became a loner aged late fifties I have joined a lot of things, favourite charities, part time jobs, U3A , a local club set up by a kindly man for local loners, dating agency, even a church.
I met several people of course, with whom I had something in common however considering the large number of people I met there were few intimate friends.
It's very easy for someone who is able bodied to join things: it's very hard to find a companion who is a friend, that is if you are a quiet person or have unusual tastes like going camping up the Highlands. However do please remember that husbands are not guaranteed to be companionable.
Most people bore me and I'd rather have a dog companion.