Tim McGraw turned to social media to pay tribute to his wife Faith Hill on her birthday on Saturday (Sept. 21), calling her his "best friend" and "our center" in his family.

The country superstar posted a very casual picture of Hill to his Instagram on Saturday, in which she is shielding her eyes against the sun and smiling into the camera.

"Our center....," he writes to accompany the photo. "She is my wife, she is the mother of my girls, She is my best friend, My lover, My tether in the storms, I love her. I love her. I love her."

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"Happy birthday baby," he concludes.

Hill is turning 52 on Saturday. It's not unusual for McGraw to use social media to mark the occasion of his wife's birthday; in 2018, he shared a photo montage of Hill to celebrate.

Hill marked McGraw's 50th birthday in 2017 by leading a concert audience in a massive singalong at a tour stop in Indianapolis.

McGraw and Hill married on Oct. 6, 1996, and they welcomed their first child, Gracie Catherine McGraw, on May 5, 1997. Maggie Elizabeth followed in 1998, and Audrey Caroline was born in 2001.

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