Blake Shelton opened up about his four-year relationship with fellow musician and “Voice” coach, Gwen Stefani.

The 43-year-old singer got candid about his life with the former No Doubt frontwoman, 50, in an interview with Martina McBride for her “Vocal Points” podcast. The star noted that his improbable romance with Stefani is, in a way, more shocking to him than being named People’s “Sexiest Man Alive” in 2017.

“If you thought the People magazine cover was shocking, mine and Gwen’s relationship is probably the biggest head-scratcher,” he joked (via People).

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Shelton and Stefani got together in Season 9 of “The Voice” in 2015, which was her second time as a coach. Shelton admitted to McBride that, during Stefani’s run in Season 7, he didn’t get a chance to really know her.

Gwen Stefani and Blake Shelton pose for a photo. (Getty)

“I’ll even say that she was, of all the coaches, the least that I had gotten to know the first season she was on the show because she had just had a baby, and I mean just had a baby,” he said. “And so any time there was downtime, she was busy. She was gone, she was on her trailers, she was taking care of the baby, you know, and there was never those moments that usually happen on this show, where at the end of the day we’re sitting around out here at the couches and having a drink, talking, laughing.”

Despite getting a slow start on their relationship, Shelton says that they’ve both rubbed off on each other after four years of dating. Specifically, he notes that he got the notorious rocker into country music.

Gwen Stefani and Blake Shelton attend the grand opening of the "Gwen Stefani - Just a Girl" residency at Planet Hollywood Resort and Casino. (Getty)

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“If she was sitting here, she would tell you she’s never going to be good with names. She can’t remember anybody’s name,” he explained. “She knows so many songs now. And in fact, I would say that Gwen, I don’t know how she’d feel about me saying this, but I’m going to say it. I bet she listens to probably 75 percent country music now.”

He also noted that she now uses country playlists to put her kids to bed at night. She shares children Kingston, 13, Zuma, 11, and Apollo, 5, with ex-husband Gavin Rossdale.

Meanwhile, Shelton has been on a musical journey of his own as he gets to know his girlfriend’s hits.

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“I’ll go watch her show in Vegas because you got to remember I’m playing catch-up on Gwen Stefani,” he explained. “I knew who No Doubt was, and Gwen Stefani, but only the big hits, and then you go see her show in Las Vegas and you start going, ‘Oh my God, that one too, that song. Oh that’s you.’ You know? And it’s just a crazy… It gives me goosebumps talking about it because of the impact she had, especially as a female rock, ska, whatever you classify it, as just to have the impact that she has is pretty crazy.”