The cute couple kept things super professional during their strategy meeting, not making any references to their relationship. However, it was evident in their sly smiles and fleeting glances that the spark is still very much alive.
Shelton also expressed how excited he was that Stefani had returned to The Voice after serving as a coach during seasons seven and nine. The pair connected through shared heartbreak last season, as Stefani split from husband Gavin Rossdale and Shelton divorced wife Miranda Lambert.
"Here you are. I knew you were coming back for season 10," the 39-year-old country crooner said, beaming at Stefani.
"Thank you for having me back, Blake," the 46-year-old "Make You Like Me" singer responded earnestly.
And if you thought Shelton only asked his girlfriend to be the Team Blake mentor because of their adorable relationship, the "Came Here to Forget" singer argued that the decision was made entirely in the interest of winning this season.
"I brought Gwen in because if there's anybody who understands what a battle round is, it's somebody who's been a coach," Shelton explained. "She knows what it takes to win this thing."
While Stefani didn't actually win during either season that she served as coach, she did get contestant Jeffery Austin to the finals last season.
For Stefani's part, it sounds like she agreed to be the mentor out of pity more than any sort of romantic attachment.
"I would love to help you," the singer told Shelton as they met with Team Blake contestants Brittney Lawrence and Paxton Ingram. "Because I think you need a lot of help."
"What is that supposed to mean? What are you trying to say?" Shelton asked, pretending to be offended as Stefani just laughed and laughed.
Currently, it seems that Shelton's biggest rival this season is Aguilera, Stefani's replacement on the coaching panel. And, if the bombastic stunts she's already performed this season are any indication, Shelton could have a real challenge on his hands -- as could fellow coaches Pharrell Williams and Adam Levine.
Check out the video below to see Aguilera's spontaneous, epic duet with Voice hopeful Joe Maye last week.