Ricki, I'm afraid all I can offer is my own experiences in the hope that maybe you'll find some similarities and hopefully a better understanding of "why". For me personally a lot of the feeling disconnected and in some ways disconnecting myself is all about pain. For example, I've got some friends at work but I don't get too close to anyone here. I think it's because of the "inopportune" times that we moved when I was younger.
Sure we moved when I was very young but before a certain age it doen't seem to matter so much. But we moved to Troy when I was... well, honestly I don't know. I just remember being 3 or 4 and being in that house. I started kindergarten when I lived in that house. I met some new people (I don't really remember them) and then halfway through the year we moved. To an adult it's not really that far between the two houses (maybe about half an hour) but to a 5 year old they're worlds apart. I just kind of had to move on.
We moved again the August before I started first grade (6 or eight months after that "first" move). Again, it wasn't so bad for an adult but it was another world apart for a kid. Things were very much "not good" for me in grade school so I ws kind of looking forward to starting over in junior high (which in that school started in eigth grade). We were in the same house but there would be some kids who didn't know me, so it was like a new start. Darn it, half way through the year we moved 250 miles away. That killed me. We hardly got to see family, let alone friends. So I had to leave those friends behind too.
So not only did I have to learn to be very careful who I "let in" so I didn't get hurt, now I was learning that it wasn't really worth letting ANYBODY in because eventually you would have to leave them behind. Sure enough, four and a half years later I graduated high school and most of us went our separate ways. Let them go, Casey, let them go. It hurts less.
I quit my first job after only six months, but I did it so badly (yes, I was young and stupid) that I felt uncomfortable seeing anybody from there. Let them go. My next job lasted six and a half years before we got the news that the company really was going bankrupt but we were going to be out of a job in a month. Between the Christmas rush and everybody trying to find a new job quickly, not to mention my own self esteem problems, I didn't really feel comfortable asking to keep in touch. Everybody just kind of wanted to get the heck out of Dodge. Let them go Casey.
So it had become a vicious cycle. It hurt too much to let people get close, and even if I did I was just going to have to let them go eventually, mostly because I wasn't worth keeping in touch with (my self esteem issues rearing its ugly head). I learned how to deal with feeling disconnected: ignore it. So I was disconnecting because I felt disconneted because I was disconnecting because...
Like I said at the beginning, it's all about pain. At least it is in my experience. The thing is what do you do about that pain. But that's the million dollar question, isn't it?