Blake Shelton Wishes Girlfriend Gwen Stefani a Happy Birthday: 'Special Day for a Special Lady'

Happy birthday, Gwen Stefani!

The pop icon turned 51 on Saturday and her longtime boyfriend Blake Shelton marked the special occasion with a sweet Instagram post.

“It’s a special day for a special lady in my life,” the country star, 44, wrote alongside a photo of the pair. “Happy birthday @gwenstefani, I’d write a song for you every single day if I could…”

Stefani also posted on Instagram for her birthday, sharing a photo of her from when she was a baby. “Thank u for all the bday wishes! gx,” she captioned the picture.

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Stefani and Shelton have been dating for nearly five years and recently teamed up for their fourth duet together, titled "Happy Anywhere." In July, Shelton opened up to PEOPLE about the new song and their relationship.

"An Okie boy and a California girl look on paper like an unlikely match, but what matters is she's a great human being," said Shelton. "She is the most understanding, kind-hearted person I've ever met and I learn something from her every day.”

Amid the ongoing coronavirus pandemic, the two Voice coaches holed up in Shelton's cherished Tishomingo, Oklahoma, ranch, taking advantage of the added uninterrupted quality time. Stefani’s sons, Kingston, 14, Zuma, 11, and Apollo, 6, also joined them at the ranch.

"The simple pleasure of being together in one place for an extended period of time has been a real gift," Shelton said. "We cook, we clean, we ride four-wheelers and we just enjoy being with each other and with family."

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During a recent episode of The Ellen DeGeneres Show, Shelton discussed how the couple made the music video for “Happy Together,” which featured years of family videos.

"Gwen's brother [Todd] was in quarantine with us too in Oklahoma and, I don't know why, over the years I've kinda become a video camera geek, even though I don't even know how to work these things," Shelton said in the virtual interview in late September. "I've got a few cameras that I have no business owning, let's just be honest. But Todd's really good at that stuff."

To make the music video, Shelton said they went through over five years' worth of home videos captured on Stefani's phone, with some new shots captured by Todd.

"He edited that thing and put the video together, and it ends up being maybe my favorite video I've ever had," he said. "It's just so honest and real, you know?"