I agree OP but also would nuance a bit - I think it’s true that nobody will ever fully and completely understand us and always be able to give us the support we need; and that fact can be very painful, especially in hard times and I think especially for those of us who didn’t have the love and support we needed as children (because childhood would usually be the one time in life that you DO receive mostly good-enough unconditional love, and not receiving it can be v damaging as we know).
But then I think that even though what you said is true, there ARE / CAN BE people who care about us even though they sometimes let us down and sometimes don’t understand us; and we can surround ourselves with people who are basically good people, who we can be close with in different degrees, and all of whom sometimes understand us and sometimes are there for us. And then we are not completely alone, even while knowing that nobody is completely reliable or completely there for us.
We’ve been in lockdown for so long here in England - I feel like I can’t really remember not being - and it’s been really noticeable to me how important it has been for me to keep talking to friends. Also very noticeable that all my friends have ‘let me down’ ie been unavailable when I really needed them, or totally failed to understand me - as I probably have for them, because we’re all going through a hard time - but always when one person has been totally flaky, another has been kind and supportive. So even though it’s upsetting, I can kind of see that I need to make allowances for everyone and that in the round it’s better to be surrounded by others - emotionally and on Skype etc - even though everyone will sometimes let you down.