Austin (Must Love Danger Book 6) by Emily Jane Trent

Navy SEAL Austin Burke must protect his best friend's sister, Marianna Suarez, from a dangerous threat that puts her life at risk. He’s out of the Navy and divorced, so for the first time, he’s free to court Marianna. But protection comes first. As they work together to safeguard her mother's priceless paintings, they can't deny the intense attraction between them. After her mother’s death, Marianna finds purpose in honoring her mother by displaying her artwork in a prominent museum. But her ex-husband threatens to destroy her and the precious paintings. When threats turn to physical violence, her only hope of protection is a retired Navy SEAL. In the throes of danger, the attraction is strong. Austin is her brother’s best friend, and he’s been off limits—until now.