It hurts so much when the one you love has a broken heart from the one they love, and it's not you. Then they have the nerve to tell you that you have no idea how they feel, when you just watched them go out, fall in love with someone that's not you, and get their heart broken.
They tell you that you don't know what love is.
It's them who doesn't know. They're staring it blindly in the eyes and can't even notice it.