"To get people on his team, Blake will say, 'I don't want to brag, but my girlfriend is the queen of ska,'" the source tells Us.
Fans might experience some déjà vu when season 11 of the NBC sing-off launches September 19. "Blake used to say, 'My wife, Miranda Lambert, is the best female country star,’" the insider recalls. (Shelton, 40, and Lambert, 32, split last July after four years of marriage. Lambert has served as a mentor for Team Blake, a role later doled to his current girlfriend, Stefani, in season 10.)
But Shelton is not just name-dropping the 46-year-old mom of Kingston, 10, Zuma, 7, and Apollo, 2 (with ex-husband Gavin Rossdale), who stole his heart on The Voice set last October when they both served as coaches in season 9.
"He talks about Gwen a lot," reveals the insider. "He's always gushing about her and is so happy!"
The feeling is definitely mutual. On Shelton's 40th birthday June 18, Stefani, 46, joined the country singer on stage at his concert in Colorado. After a performance of the couple's new duet, "Go Ahead and Break My Heart,” the "Used to Love You" singer planted a huge kiss on Shelton for the crowd and asked the audience to wish him a happy birthday.
The next morning, Stefani gushed to her Instagram followers: “Happy birthday to @blakeshelton literally my favorite person ever."