I feel some kind of pervasive core loneliness too. Spiritually I actually think the universe is god. I think that "god" might have been lonely and decided to conceive of "himself" as a bunch of separate consciousnesses to alleviate loneliness...

I think this always feeling lonely thing happens to those of us who had bad mothers. I also think it happens if you don't have enough authentic close relationships. Finally, I bet to some extent, it happens to everyone.