Gwen Stefani made her return to The Voice in Monday's season 17 premiere -- but boyfriend Blake Shelton might not be that happy about it!

The last hopeful of Monday's blind auditions was 22-year-old singer Kyndal Inskeep, who took the stage at the end of the episode. Her soulful rendition of "Never Been to Spain" wowed the coaches, but may have caused a rift between the show's power couple -- as Stefani took the opportunity to use her block on Shelton as she turned her chair to make her case for the young performer to join her team.

"It's never good when your girlfriend blocks you," Shelton lamented of not landing the young country singer. "This brings it to a whole new level. This was on national television!"

"You're personally responsible for breaking up one of America's favorite couples," fellow coach John Legend joked to the young hopeful, calling Stefani an "assassin" after she made her pitch for joining her team. 

"I'm so inspired. I haven't been here in a while, so I'm ready to go," she told Inskeep of why she should pick her over Clarkson. "She's doing a talk show, she has a hundred kids. She has a lot on her mind!"

For her part, Clarkson has fully embraced sitting in former coach Adam Levine's old chair, striking up an immediate rivalry with Shelton. "Blake got blocked by his girlfriend! Which makes me so happy," she gleefully told the cameras.

Powerless, Shelton admitted to the young singer, "I'm very happy for Gwen if she gets you," joking, "I don't care about Kelly that much." He also tried to sway Inskeep to Stefani's side with a playful threat: "She put our relationship on the line for you!"

The gambit ultimately paid off, as Inskeep chose to join Team Gwen. "It's really fun to use your block," Stefani told the cameras with a smile. "It really worked out for me."

"I'm really looking forward to the tabloid that says, 'Gwen Blocks Blake on National Television,'" Shelton grumbled. "That's gonna be a lot of fun."

.@gwenstefani will do anything to get @kyndalinskeep on her team. 😂 Even block @blakeshelton! #VoicePremierepic.twitter.com/cvOyVZQmU3

Poor Blakey. pic.twitter.com/F9ZVIDLcY8

ET spoke with Shelton earlier this month, where he opened up about his girlfriend -- and her competitive streak -- returning to The Voice this season. 

"You know, she wants to win and I want to win and that's what they pay us to do on this show is to try to win the show," he said. "It's harder for [Gwen]. She's not, she's not competitive. She'll be the first to tell you right up until it gets competitive and then all of a sudden she is."

The Voice airs Mondays and Tuesdays at 8 p.m. ET/PT on NBC.

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