Demi Lovato's 'killer duet' partner has finally been revealed.

Earlier this month, the Really Don't Care singer posted a pic on Instagram of just two thumbs ups (one a man's) along with the caption: "Recorded a KILLER duet today.... Can you guess who it was with???"

"It's so easy to do a duet that's a love song, because our relationship isn't really that. But there is love there for a friend, you know, and it's beautiful to just talk about.

The former Jonas Brothers star continued: "Any kind of relationship can hit a point where if it's not stable, it's not secure, then it's like an avalanche crashing down and that's what that song is about.

"Her voice is amazing on it and it feels good. I'm excited for people to hear it."

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