Demi Lovato and Nick Jonas have been through a lot. The former tween stars grew up together on the Disney Channel, but now that they're adults, the pair's bond has gotten even stronger. In addition to starting their own label and sharing a tour, the pop stars hang out all the time — so much so that, when Lovato was out with her new man, Jonas tagged along as her third wheel.According to E! , Jonas made a very special appearance during Lovato's date with her new maybe-boyfriend, Luke Rockhold. Lovato and the mixed martial arts fighter were spotted holding hands and looking very couple-y while out at a UFC fight, but they weren't alone. Jonas' SnapChat revealed that the "Jealous" singer was also in attendance and hanging out with his BFF — though you wouldn't know it from this picture: