When: September 2001 - June 2002

Not only did John date this former Party Of Five star, but it's been rumored that his breakout single "Your Body Is A Wonderland" was actually inspired by her. For the record, whether it was or not, we agree that her body is. The two dated for the better part of a year in 2002, and it's said that the relationship fizzled due to John's rigorous touring schedule that year. 

Smash Probability: They dated for almost a year. Come on.