Well, you started with the easy questions Kevin. I am as isolated as I am for many reasons. One reason would be that I was surrounded by assholes when I was growing up, leading to things like someone trying to get to know me being a very unpleasant experience. Also leading me to being terrified of inconveniencing people which if I assume that they experience getting to know them the same way I do leads me to not trying to get to know anyone. So that's pretty isolating.
Your definition of relationship and community sound about right. I have hung around message boards trying to be being insightful or helpful(including this one), but that has never resulted in relationships or community. Attending gatherings IRL has not been successful either. I can attend a poker game or a board gaming group but they are not close-knit groups, because close-knit groups invite their friends... not me. So the groups that I have access to are groups that are excellent for performing a specific activity with strangers or, at best, acquaintances but useless for forming relationships. At least that is my understanding and that is my expectation for this forum. I'm sure I could hang around here being insightful and shit but I don't understand how that could result in any real relationships.
I have been in therapy about a year. It has been very helpful with respect to my relationship to myself.