Blake Shelton Gwen Stefani song
Blake Shelton says his duet with girlfriend Gwen Stefani may be the best song he’s ever written. Above, he appears at the “The Voice” Karaoke for Charity event in Hollywood on Thursday, April 21, 2016. Getty Images

Blake Shelton is really proud of his duet with Gwen Stefani for his forthcoming album, “If I’m Honest.” Stefani, who’s been dating Shelton since November, revealed earlier this week that she was featured on her boyfriend’s record. During an interview Friday, Shelton opened up about the process of creating the song, “Go Ahead and Break My Heart.”

“We finally got a mockup 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,’” he told Entertainment Tonight. “It’ll be our way to announce that yes, we have a duet together.”

The “Voice” coach said not only did they collaborate on the song, but Stefani helped him write it. Shelton explained that it’s rare for him to write with other people, but he’s pleased with how the track came out.

“[The song] is very personal for us both because, you know, we obviously have this bond that is remarkable together,” he said. “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.”

He continued, “I hesitate to brag on it too much, but I really think that it’s as good of a song as I’ve ever written in my life.”

As for other songs on the album, Shelton previously revealed that it won’t be filled with “juicy details” about his July 2015 divorce from Miranda Lambert, but will have songs about his efforts to get over the breakup and move on with his life.

“It’s not like there’s all these juicy details [in the record],” he previously told CMT After MidNight. ”But [country music] lends itself to emotions and things that you go through when you go through a divorce and, more so, the getting over that and moving on and finding someone else.”

“If I’m Honest” will be released May 20. Shelton released the first single, “Came Here To Forget” — about drowning a broken heart with alcohol — last month.