We all have days or incidences when we feel down and alone but this too usually passes.

I love the conclusion of this article by Marcia Reynolds Psy.D.:

You Could Be Lonely Even if You Have Friends

"You may not be alone, but do you feel empty? You can’t fill this emptiness with food. Feed your heart by being seen and heard, by giving others the gift of your full attention and by appreciating the beauty in the world around you."

[psychologytoday.com]

Many humans hold the belief that they can "understand" others . . . . I do not hold that belief, because I can't even understand myself sometimes. So with that out of the way, it becomes clear that we are isolated, simply by the nature of our own existence. I don't expect to meet my twin, and even if it were possible, even twins become separated as a result of different experiences coupled with time. We know that "Experientia docet.", That is, experience teaches . . . . so we are born, live, and die in our own isolation, whether we like it or not. We have to either accept that, and move on, or lie to ourselves, and not accept it. Beyond that, one might question, why bother to exist at all, but even if we are unable to understand others fully, it is community and social life that helps us grow intellectually and brings us back from that void.