Nick and Miley, 22, dated from 2006 to 2008 and have clearly remained friends. He's also stayed pals with his brother Joe's ex-girlfriend, Demi Lovato. In fact, the two are going on tour together next summer and have started their own record label.
"Demi, obviously wife, because we're like brother and sister and friends," he admitted to Britain's Capital FM. After his semi-incestuous comment, he added, "I'd prefer to spend life with her, as opposed to the others."