Garth Brooks has been open about the mistakes he made during his first marriage to Sandy Mahl, with whom he shares Taylor, 31, August, 29, and Allie, 27. “I sucked at being a husband,” he’s said. “I was horrible at it [and] I was horrible at being a dad. I had to get my s–t together.” The “Friends in Low Places” singer did just that when he wed fellow country singer Trisha Yearwood in 2005. “After Garth and Sandy divorced, Garth was a single dad and it was a real learning experience. Fortunately, Trisha was there to help steer him in the right direction,” says the source. Seventeen years later, they’re more in love than ever — and still having a blast. (In 2021, their cohosting gig on The Ellen DeGeneres Show went viral thanks to their tongue-in-cheek duet, “Wife Is Always Right.”) “They can be very silly with each other,” says an insider of the pair, who are working on a new duets album. “They both know how lucky they are.”