Luke Bryan's wife Caroline turns 39 on Monday (Dec. 31), and the superstar singer took the time to share a sweet public message about what makes her so special.

The "What Makes You Country" star turned to Instagram to convey his love for his wife on her special day, honing in on her selflessness and how she's the best support system to him and their children — two boys biologically and the couple's nephew, whom they adopted.

"Happy Birthday to the love of my life," he says. "Thank you for handling everything our crazy life throws at us. Thank you for the way you love me and our children. You always put everyone else first. I love you to the moon and back."

Remember How Luke Bryan Celebrated Turning 40?

Bryan accompanied the kind words with a wry photo of his wife as she stands in front of one of his plaques commemorating his No. 1 hit, "Home Alone Tonight," subtly flashing the middle finger.

"This picture sums up your amazing personality," he jokes.

The family evidently spent Caroline's birthday skiing, as evidenced by another post Bryan made from a ski lift:

The couple celebrated their twelve-year anniversary on Dec. 8. Bryan often portrays his wife as the rock of the family who is a loyal supporter of his career in country music. Caroline is also the force behind Brett's Barn, a sanctuary on the couple's farm that houses a myriad of animals and serves as a therapy center for children who have ailments and disabilities.

"Caroline loves it. It's just been really amazing watching my wife really enjoy doing this," Bryan says. "Brett's Barn is continuing to morph into something pretty amazing. We've got some really fun stuff in the horizon that we've been working really hard on to get going." 

See Luke and Caroline's Cutest Pics Together: