"The saddest thing in the world, is loving someone who used to love you."
That single word in that sentence, 'Used', Changes the whole flow of it.
It's not like other things I've seen where it says "loving someone who doesn't know you exist," or "loving someone but being in the friend-zone," or something along those lines. No, with the word 'used' in there, it acknowledges the previous connection from the broken relationship, which I believe, is more powerful then having never been with that person and loving them. You know them on a level that not too many others will ever know them, and they know you in that way too. You got to know all of their flaws, mistakes, joys, dreams, aspirations, everything, and you love them for it all. It's not fair when a heart doesn't break even. And this says it perfectly.