Gwen Stefani seems like she's just giddily in love with Blake Shelton, and she doesn't care who knows it. The pop star posted a sweet happy birthday message for her boyfriend on Saturday (June 18), accompanied by an adorable throwback photo of Shelton when he was a kid.

Shelton turns 40 on Saturday, and Stefani — who's been dating the singer since both of them split from their spouses last year — published a picture of a young, smiling Shelton to her Twitter, writing, "Happy birthday to my favorite person I ever met @blakeshelton." She added several emojis to her post, including a cow, a bee, a flower and the hashtag #superbabe. Shelton's twinkling eyes and devilish grin in the throwback photo seem to provide an early hint at the sense of humor that would later become one of the singer's trademarks.

Stefani also gushed over Shelton in a recent interview with Us Weekly, saying she’s rooting for their relationship more than anyone.

“I’m our biggest fan,” she says."I actually feel like I'm not in my own life, because I'm not. I'm in a different life all of a sudden. I'm so blessed and I feel like I believe in my path. Now there's all these miracles around me!"

Stefani and Shelton performed their duet, “Go Ahead and Break My Heart,” at the Billboard Music Awards, and beamed at one another throughout the performance. They co-wrote the song near the beginning of the relationship, when they were still on The Voice together. Stefani has said that the relationship with Shelton ‘saved’ her. 

That's a thought that he echoes. "All of a sudden this thing just happened because of some things we were going through and it saved my life, period,” he says.

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