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Adam Levine‘s decision to leave his longtime post on The Voice came as a surprise to many fans, but insiders close to the singer say he’s been preparing to take a step back from the hit singing competition.

“He’s been wanting to move on for a while,” a source tells us of the Maroon 5 frontman. “They wanted him to stay but he just really wanted to move on. It’s something he’s been talking to [host] Carson [Daly] and the other coaches about for some time.”

According to the source, Levine, 40, was not a fan of some of the updates made to The Voice for season 16, notably the Live Cross Battles, which debuted in April. In this new round, two coaches go head to head in a “live schoolyard pick” by each selecting one artist from their team to go up against another team’s artist. Each artist performs an individual song, and their fate is decided by a viewer vote.

In a preview of the Live Cross Battles, Levine said the round made the show feel like “the wild west out there now” — and this wasn’t a good thing. His team took a major hit, leaving the musician with only four contestants. By the time the show arrived at the Top 8, Levine’s entire team had been eliminated.

“He really didn’t like some of the changes to the format of the show last season, and it’s just time for him to leave,” the source continues. “It wouldn’t be surprising if he came back to visit the show though. There’s new music coming soon for him, he’ll be touring and he plans to continue acting. He’s staying busy.”

Adam Levine. TRAE PATTON/NBC/NBCU PHOTO BANK VIA GETTY

Levine’s chair won’t be empty for long: three-time coach Gwen Stefani will return to the show this fall, the network announced Friday.

“Adam has always had one of the toughest schedules of the coaches. He’s been ready to move on and also have more time with his family,” a show insider says of Levine, who is dad to two toddler daughters with his wife, model Behati Prinsloo. “It’s bittersweet for everyone, but Adam is so excited that Gwen is going to take his chair. She’s beloved by everyone at the show and at NBC.”

Levine himself opened up about his decision to leave The Voice in a lengthy note posted to Instagram on Friday, hours after the news first broke.

The singer posted a 2012 Rolling Stone cover featuring himself with then-coaches Christina Aguilera, CeeLo Green, and Blake Shelton. The foursome were the original coach panel for the first three seasons.

In the caption, Levine recalled how he first landed the gig, which lasted over eight years and 16 seasons.

“About 8 years ago, Mark Burnett convinced us to sign up for this show where you sit in a big red chair with your back turned away from the singers on the stage. First thank you must go to Mark. ❤️ We had no idea what we were doing or where it was going,” he began the message. “After the first day of shooting, I sat there, stunned. I said to myself “there’s some magic here. Something is definitely happening.” It went on to be a life shaping experience that will be close to my heart forever.”

He then went on to thank numerous members of the cast and crew, including host Carson Daly (for “making sure our shoes were tied and we had our lunch boxes”), musical director Paul Mirkovich, and, of course, former and current coaches.

But he reserved a special, more colorful shout-out for his BFF Shelton — or, as he puts it, “BLAKE F—ING SHELTON.”

“I couldn’t hide my love for you if I tried,” he addressed the 42-year-old country star. “Seriously. I tried. Can’t do it. Our friendship is and always will be one for the books. Whatever this whole surreal experience was, I’m just happy I got to experience it with you. You’re my brother for life.”

He also made sure to extend heartfelt thanks to “the loyal Voice fans.”

“There’s literally no show without you guys,” he added. “For me, it was time to move on. Your support has meant EVERYTHING.”

Levine signed off by tipping his hat to his late manager, Jordan Feldstein, who died of a blood clot in December 2017 at the age of 40.

Daly announced Levine’s departure Friday morning on Today — saying the “beloved coach and friend” would be missed.

Levine was one of the original coaches who launched The Voice when it premiered in April 2011. He and Shelton have remained in the show’s iconic red chairs ever since, though other coaches have rotated.

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The current lineup includes John Legend and Kelly Clarkson, both of whom are returning for season 17.

Over the course of his 16 seasons, Levine has won the show three times: first in season 1, with Javier Colon, and then again in season 5 (Tessanne Chin) and season 9 (Jordan Smith).

He’s also developed a hilarious frenemy relationship with Shelton, which many credit with part of the show’s success.

“He’ll always be a cherished member of The Voice family,” Daly, 45, said on Today, praising Levine for “inspiring many of the artists who he worked so closely with over the years” and helping launch The Voice. “Of course, we wish him nothing but the best.”

Fellow coaches were quick to offer their thoughts via social media.

Clarkson, 37, shared a few sentiments on Twitter, writing, “Found out last night about Adam leaving The Voice & while I get that he’s been doing the show 4 a while & wants to step away, it will be weird showing up 4 work & he’s not there. To start an amazing show from the ground up is a big deal!”

Close pal Shelton was having difficulty accepting the news. “Having a hard time wrapping my head around Adam not being at The Voice anymore,” he wrote. “After 16 seasons that changed both of our lives. I only found out about this yesterday and it hasn’t set in on me yet. Gonna miss working with that idiot.”

Responding to Levine’s Instagram post, newest coach Legend, 40, wrote, “We’ll miss you, brother.”

The show issued a statement Friday morning. “Our friend and coach Adam Levine made the decision not to return next season. We’re going to miss Adam, but The Voice is family and with family it’s ‘see you soon,’ never ‘goodbye,’” The Voice Twitter account posted. “Gwen Stefani returns with Kelly, John, and Blake on The Voice stage this fall. Join us in welcoming back Gwen, and sharing our heartfelt gratitude to Adam!”