Leaving a tribe is painful.
No, I'm not speaking in hand-wavy metaphors. Literally, loneliness is a biological feedback loop to urge us back into a tribe. The reason being is that evolutionary wise, reliance on a tribe was a survival mechanism that we still benefit from this day. Only the most extreme introverts (and this is exceedingly rare) can truly live the lifestyle of a hermit apart from a family, a community, a tribe, or even strangers.
I know this pain. I've left or lost my tribe multiple times.