Felt like it lasted: An eternity
Really lasted: Three years
Justin and Britney's breakup is one that we'll never get over, no matter how much time has passed. They spent their childhood together while working on The Mickey Mouse Club and went on to become pop sensations. They began dating in 1999 though didn't officially confirm the relationship until a year later. In 2002, they parted ways, leaving us with multiple cryptic breakup songs and a pile of tear-stained photos ripped from the pages of Teen People.