Blake Shelton Opens Up About His Gwen Stefani Duet on 'Ellen': 'I Don't Know That We Ever Really Saw It Going

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When it came to writing a song about his relationship with Gwen Stefani, Blake Shelton went back to some teenage romance staples.

“I only started the song to impress her,” he told Ellen DeGeneres on Monday’s episode of her show. “To be like, ‘Hey, I’m writing a song about you.’”

WATCH: Blake Shelton & Gwen Stefani Heat Up the Billboard Music Awards With Romantic Duet

But his plan backfired slightly when Gwen contributed her own verses to the tune, “Go Ahead and Break My Heart.”

“I sent it to her, and she wrote the other half of the song,” he said with mock exasperation. “It’s like, ‘Oh, she just one-upped me.’”

The country crooner knew he had something special with the song, but claims he never anticipated its overnight success.

“When we wrote the song we never saw it going there,” he said. “I don’t know that we ever really saw it going anywhere.”

WATCH: EXCLUSIVE: Blake Shelton Admits Writing Country Duet With Gwen Stefani Was a Way to 'Impress' Her

The Voice coach previously opened up to ET about “Go Ahead and Break My Heart,” saying, “It was just kind of something for she and I to help us feel better about what we were going through.”

The tune quickly reached the top of the country charts and the couple performed it both on The Voice earlier this month and at the 2016 Billboard Music Awards on Sunday night.

“The last year of my life has been nuts, it’s been crazy,” Shelton told DeGeneres of the year that has included his divorce from wife Miranda Lambert and new romance with Stefani. “I just figure if all the magazines are going to cash in on me, I might as well too.”