Thanks for all the responses. Some very insightful and thoughtful comments.

I understand what some of you are saying when you describe being with others yet feeling like you don't belong anyway. I can be with people I know, don't know, and anything in between, and at times, for reasons that are not readily apparent, feel very lonely. On the other hand, I spend quite a bit of time alone out of choice. I have a cabin I go to with my dogs, and no one else, at least once a month. I might spend 3 or 4 days there, not talking to anyone except my dogs, some birds, a deer or two, and the trees (realizing that, with the exception of the dogs to some extent) they don't hear or understand me. These times are enjoyable to a point. I want to get to a point where loneliness doesn't bother me anymore, regardless of where it happens, in the city, at my home with my family, or out in the woods on a long hike. I want to embrace it if I can as a normal part of my life, of life in general, if that is truly possible.