It's easier to write about heartbreak after you've had your heart broken. You have more material to draw from, you can extrapolate from your own experiences and make reasonable assumptions about how your characters would feel and act.
Patrick RothfussSimmon pushed his hair out of his eyes, laughing boyishly. "You can't argue your way out of this one! She's obviously stupid for you. And you're just plain stupid, so it's a great match.
Patrick Rothfuss