Blake Shelton Opens Up About 'Very Personal' Gwen Stefani Duet, Says It Might Be the Best Song He's Ever Written

Blake Shelton let girlfriend Gwen Stefani tweet a photo of his upcoming album, If I'm Honest, earlier this week, and with the picture came an important reveal: The couple collaborated on a song!

"We finally got a mock-up of the album, what the artwork was going to look like. And we flip it over and it has all the songs. I said, 'You know what? Take a picture of that and tweet it,'" Shelton explained to ET's Sophie Schillaci at The Voice's Karaoke for Charity event in West Hollywood, California on Thursday. "It'll be our way to announce that yes, we have a duet together."

Even more exciting, the couple -- who first hooked up last season on The Voice after both going through highly-publicized divorces -- actually collaborated on the songwriting process, a rarity for Shelton.

Look what I found lying round the house! 🙄#ispymyname #goaheadandbreakmyheart💔 @blakeshelton #eeeekkkk! #crazy!😝 Gx pic.twitter.com/ZI0Kz4Ve9j

— Gwen Stefani (@gwenstefani) April 19, 2016

"[The song] is very personal for us both because, you know, we obviously have this bond that is remarkable together," the country star admitted. "But the fact that we wrote a song together... I know that I don't co-write that much because I'm very insecure about it I guess and [Gwen's] kind of got her circle of people that she writes with. But for us to reach out to each other as writers, it may never happen again, who knows."