Blake Shelton Wishes Gwen Stefani a Happy Birthday: ‘I Love You so Much’

Singer Gwen Stefani turns 50 on Thursday, Oct. 3. Her boyfriend, and fellow coach on The Voice, turned to social media to wish his longtime girlfriend a happy birthday, offering sweet sentiments on her big day.

“Happy Birthday, [Gwen Stefani]!!!! ” Shelton wrote. “I love you so much it’s actually stupid… And possibly illegal in the state of California.”

Shelton’s bar, Ole Red, also took time to send greetings to Stefani, calling her the “leading lady” of the venue.

At least Stefani’s birthday falls on a day when she isn’t filming The Voice. Stefani returned for her fourth season, after Adam Levine‘s unexpected exit, which made Shelton much more comfortable than if it was somebody new.

“I have to say that it worries me not having Adam there, because he’s been there from the beginning,” Shelton shared with PopCulture.com and other media. “It would freak me out if Carson [Daly] left; we were the three that have been there all along, and it’s just odd to be honest with you.

“The one thing that makes it better and okay is that they brought Gwen in,” he continued. “Not just because Gwen’s and my relationship – it’s because she’s a veteran of that show. Also, she’s familiar with it, gets it, and that made me feel better.”

In fact, it’s Stefani who made Shelton eager to return to The Voice, for his first time ever without Levine.

“I’ve been here for a hundred years,” Shelton acknowledged to PEOPLE. “She’s been on the show; this will be her fourth [season]. It feels normal to have her back, but at the same time, it’s exciting. And at the same time, it kind of helps the weirdness of Adam not being here. To be honest, it’s strange to not have him here … He’s never not been here.

“He’s that guy that’s over there making you constantly want to strangle him, and now he’s gone,” he added. “It sucks, to be honest with you. But having Gwen back, for me, makes it a lot more fun.”

Shelton and Stefani have been dating for four years. Although they reportedly bought a house together in Los Angeles, and hint marriage is likely, the couple has yet to announce any formal plans.

The Voice airs on Monday and Tuesday nights at 8 p.m. ET on NBC.

Photo Credit: Getty images/ Patrick McMullan