"I Was a Fool" by Tegan and Sara

Before Heartthrob, I've always been a Tegan and Sara fan. Most people are familiar with some tracks off The Con (2007), but So Jealous (2004) is a personal favorite.

I was thrilled that "Closer" became a hit, but I'd have to say "I Was a Fool" is the one that's been stuck on my mind. It's definitely on the Single-on-Valentine's-Day-playlist.