The 39-year-old country singer was talking to Ellen DeGeneres in an interview that will air Monday, May 23, about performing their hit song, "Go Ahead and Break My Heart," live on The Voice and at the 2016 Billboard Music Awards on Sunday, May 22.
And the cheeky show host, after praising his and Stefani's vocal prowess, got the singer to admit that the high emotion and serious subject matter can make him and his 46-year-old girlfriend crack up!
"We kind of did laugh a few times," he admitted. "There's moments where it's like, Wow, we're singing this song like we're going to break up, and we're not breaking up right now, so it seems kind of weird," he said.
"When we wrote the song, we never saw it going there, I don't know that we ever really saw it going anywhere. I only started the song to impress her. To be like, 'Hey, I’m writing a song about ya.'"
"So I sent it to her, and then she wrote the other half of the song. I was like, 'Oh, she just one-upped me,’ so ..."
Shelton then admitted that his latest album, If I'm Honest, is the most revealing he's ever written.
"This is just full of all kinds of ups and downs. The last year of my life has been nuts, it's been crazy," he said, referencing his split from wife Miranda Lambert and his new relationship with Stefani. "If all the magazines are going to cash in on me, I might as well too."
Check out the whole interview in the video above.
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