Billy: "Have you ever dated any of the Jonas Brothers?"
Demi: "Umm, maybe."
Billy: "Which one? Joe?"
Demi: "Yeah. He's actually… he's my best friend."
Billy: "So you guys went from boyfriend-girlfriend to best friends?"
Demi: "No kind of the opposite."
Billy: "Oh? So you're dating him now?"
Demi: "Umm, yeah he is my best friend and he is incredible. He's a complete gentleman who treats me to the most amazing places. He's perfect."
The two met on the set of Camp Rock in 2007, then toured together the following year.
They recently recorded a duet called "Make A Wave."