I’m really only posting this so I can find the word again.

Sonder - from the urban dictionary:
The realization that there aren’t any main characters in the world and everyone has a complex life, thoughts, crushes, relatives, dreams and mind just as your own.

Essentially while you’re the main character in your life, you’re also a background character in someone else’s.

Coined in 2012 by John Koenig, whose project, The Dictionary of Obscure Sorrows, aims to come up with new words for emotions that currently lack words. Inspired by German SONDER sonder- (“special") and French SONDER sonder (“to probe").

As usual, feel free to disagree using this contact link. My world view is a hypothesis, not a belief.