I agree. We all must fell important so someone.
Unfortunately we seek that someone outside ourselves, this puts us in the position of being beggars: hey please tell me that I am important or I am nothing.

They rarely teach us that the person for whom we must be REALLY important and precious is ourselves.
If I value myself, rejections is handled in a VERY different way.
It still hurts, because we really wanted that person in our life, but we stay strong, on our strong legs because the one who went away did not take with him / her our self-esteem.

I rejected someone, some time ago. It was not because he was not ok or a good person. I did it because I was in so much pain for personal reasons that it was not time for me to think about love. Not his fault. Not mine. I tried to protect him from all the mess i had inside.

When rejection hurts so much, is because our self-esteem is not sound and safe. So please take care of that.
And tell to yourself all the kindest words on earth.