too beautiful

Some one said, in response to this picture:
whats the meaning behind that picture of the girl sitting in the train
To me, "the girl in the train"  is an endlessly fascinating picture, not because it is a love story; (in fact, I don’t think the person who took the photo was particularly in love with this girl), but rather that in the short time they spent together, he still remembers her. I think it’s a feeling we can all relate to; there is no English word for it. It’s a sort of curiosity, but also a longing, a sadness that we will never know.
It makes us think of the all the people we have met, even if it was for just a moment, and we wonder how their lives are now. Your first friend in kindergarten, your 3rd grade teacher, the boy who picked up your purse when you dropped it. They are as equally alive as you are, and they have a story you’ll never hear.
This picture captures the tragedy of human interaction, but also the beauty. And I think that is the meaning of the picture of the girl sitting in the train