'The Voice': Why Gwen Stefani won't be returning for season 18

Following Monday's news that Nick Jonas will be joining The Voice as a coach in 2020 (alongside returning coaches Blake Shelton, John Legend and Kelly Clarkson) fans were left wondering why Gwen Stefani would not be back on the NBC series next season -- after she just returned in season 17.

However, ET has learned that the singer's absence is part of the show's usual process of rotating coaches each season, in order to allow some of the big-name stars to continue maintaining their music careers.

In the case of Stefani, she plans to return to Las Vegas, Nevada, to resume the final dates of her Just a Girl residency at Planet Hollywood's Zappos Theater in February and May 2020 -- the same time that The Voice's spring cycle will air.

Meanwhile, Jonas wraps up his tour with the Jonas Brothers on Feb. 22, in Paris, France, meaning the cycle works with his schedule.

While viewers will have to stay tuned to see if Stefani returns for future cycles of The Voice, it seems like there's a fair chance -- given how she recently told ET that juggling the two projects has made her feel so "alive."

"I didn't expect to be doing [the Vegas show] and The Voice at the same time," she said. "I just feel like I'm alive in a way I've never been before, because I have to be! Because doing both is a lot."

Stefani kicked off her Just a Girl residency in June 2018.

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