As opposed to feeling as though life is somewhere down the street, around the corner, being experienced by those people over there and not you.
It's not connected to happiness as such, it's about meaning. But having said that, you can't have happiness without it - at best you have a sense of killing time and faith that things will come together soon enough.
Meaning involves other people and how they see us because very few of us are so emotionally disconnected that we really can't/don't care. We are, after all, social animals and not well set up for survival in isolation.
It's about the narrative, the place in the world. Whether you feel you need to justify where you are or 'fess up to your state of isolation, or whether your place makes perfect sense.
I am off-kilter. I am making do. I am having good times here and there, and feeling the right sort of feelings here and there. But it's random and chancey and in between I feel I am just existing to not much purpose or reason.