A Voice bromance was broken up when Adam Levine left the show last month.
At the Backlot BBQ with Blake Shelton for IHG Rewards Club Chase Mastercard cardholders on Friday, the "God's Country" singer told ET's Nancy O'Dell that it was "hard" for him to see Levine leave the series after 16 seasons together.
"I can't imagine, honestly, what the show is gonna feel like at first without Adam there," he confessed. "I mean, we're about to start filming the 17th season of the show, and Adam has been my frenemy from day one, you know, down there on the end."
"I think we all knew, on the inside of the show, that he was ready to make a move. For a guy like Adam, who is just -- he's the most ADD person I think I've met -- for him to have even done it as long as he did without wanting to move on to the next thing, is amazing. But I know he's happy with his decision. Doesn't mean I am, or any of us [are happy], but at least they were able to soften the blow a little bit and bring Gwen [Stefani] back," Shelton continued.
Having a hard time wrapping my head around @adamlevine not being at @NBCTheVoice anymore. After 16 seasons that changed both of ours lives. I only found out about this yesterday and it hasn’t set in on me yet. Gonna miss working with that idiot.— Blake Shelton (@blakeshelton) May 24, 2019
Levine was previously confirmed to return as a coach for season 17 of The Voice, but host Carson Daly revealed on the Today show on May 24 that he had decided to exit the series. Stefani was announced to be taking his place alongside fellow coaches Shelton, John Legend and Kelly Clarkson.
"Without Adam there, it was -- I don't know, I knew it was gonna be hard for me. We just have that thing that's just so comfortable," Shelton told ET of his reaction to the switch-up, but quickly noted that "Gwen and I click too."
The singer, who has been dating Stefani since 2015, joked that he'd "like to say that I had something to do with" Stefani coming on board, but noted they "pulled the trigger before I even had time to react."
"By the time I found out what was going on, which was only about 12 hours before the announcement, they had already reached out to Gwen's camp and said, 'Look, Adam's decided he's gonna move on, we're ready for Gwen if she's in,'" Shelton recalled. "I'm like, trying to get in the middle of this, literally, I got on the phone with one of the NBC executives, and I was saying, 'Hey man, if Adam's gonna do this, we have got to--' and before I could even finish my sentence, she said, 'Blake, it's done. What are you doing?' And I went, 'Oh, OK. Perfect.'"
With Stefani by his side on The Voice, Shelton's spirits have certainly lifted. The success of his single, "God's Country," has helped too.
"You know... this could be the biggest record I've ever had. I mean, it certainly looks like it could be," he shared. "And for it to be 18, 19 years now, into my career, and to just now be having that record is -- I never would have dreamed. I literally thought those days and those types of records for me were 10 years ago, 5 years ago, and everybody has their moment and then it's over."
"I couldn't be more thankful and appreciative. I think I appreciate something like this now more than I ever would have in the past, because like I said, I kind of felt like my window of time and awards shows and stuff had passed. To have this song, this late in the game... it's just such a gift," he added of the song, which became his 14th No. 1 on Billboard's Hot Country songs chart. "I'm having a blast with it."
See more of our interview with Shelton on Monday's ET. Find out how to watch here.