I wanted to post to see if anyone else feels the same way as I do, or has suggestions for me. I have felt like this for my entire life really.
Basically, I find that when I am able to spend time with friends, I usually have a great time and am really happy. But then, when we all leave and go back home and I am by myself again, I start to feel very sad and almost depressed.
As a recent example, I recently connected with an old friend from college over dinner. We both had a really nice time and managed to catch up on everything that had happened in our lives since we graduated. After the dinner, I went back home, and just started to feel extremely sad knowing that I may never see him again, and that the whole experience was over.
This seems to happen almost every time that I spend time with people that I enjoy spending time with, particularly when I visit family. I know that part of it is just that I have so little of a social life, that I cherish the few opportunities I have that much more. But even when I have a fairly active social life I still felt this way every time we'd do something together. It is extremely hard for me to say goodbyes to people because of this too.