The 26-year-old DNCE frontman gushed about the 23-year-old singer in an interview with E! News on Monday. Jonas and Lovato are longtime friends who dated for a few months in 2010.
"She's family. We've known Demi for so many years," he said of himself and brothers Kevin and Nick Jonas. "We've performed with her, toured with her. She's just incredible."
"It's not always the case [to stay friends]," the star added. "Sometimes you have to know when to fold the cards. I don't think of her as an ex. We're really good friends. We've gone through so much together and we're really close now."
Jonas and Lovato skyrocketed to fame after starring in Disney Channel's Camp Rock (2008) with Kevin and Nick Jonas. The siblings were performing at the time as the Jonas Brothers and have since pursued solo careers, along with Lovato.
"We've seen each other go through tough times, good times, in and out of relationships," Jonas recently told Billboard. "It's funny to think back on [us dating] now. It feels like we were children, although I guess we were."
"She is like a sister to both [Nick and me], and it's great to know we all have that support," he added. "She's [currently] the best version of herself I've ever known."
Lovato and Nick Jonas are presently touring together, while Jonas and DNCE are on the road with Selena Gomez. Lovato admitted she encouraged Nick to break up with his ex-girlfriend, Olivia Culpo, in the July 30 issue of Billboard.