This seems to have happened to me, I have had several serious illnesses in the last few years which have made it very difficult to meet up with people or make regular commitments to voluntary work and so on, and I've gone from knowing loads of people locally to having hardly any friends. I've been feeling very lonely. I know lots of people online, which is lovely, but it's not the same.
I've just started to get to know people through joining a new church. It's still quite hard for me to join in things because I have chronic fatigue, but people are making an effort to get to know me, because it's a friendly church.