When: April 2008-March 2009

In 2008, John entered into what soon became a high profile relationship with Jennifer Aniston. Though the former Friends star and Hollywood heavyweight is nearly ten years older than John, the two enjoyed a storybook romance for the better part of a year. Since their split, John's been quoted as saying, "I'll always be sorry that it didn't last. In some ways, I wish I could be with her." Sorry, John, she just got engaged to actor/director/screenwriter Justin Theroux. Will Jennifer Aniston wind up being the one who got away? Time will tell.

Smash Probability: We'd be hard pressed to believe that these two were just...friends.