Burning Heart by Jen Talty

Air Force Fire Protection Specialist, Declan Rivers, gave his heart once, and it got charred beyond recognition. While deep down he still wants it all, the career, the wife, the family, he can’t put himself out there. That is until his best friend’s wedding where he finds comfort in the arms of Becca Knowles, a sexy senior firefighter and co-worker. He’s had eyes for Becca since she first stepped onto the base, but after one hot night, they decide it’s best if they remain friends.

Well, he decides thanks to that aforementioned reluctance.

Becca Knowles understands a broken heart and after a one-night stand with Declan, she vows to give up on men for a while and focus only on her career. Only that declaration lasts just one measly month when she first finds out she’s pregnant, and then that her younger sister is missing. Not knowing where to turn, she asks Declan for his help, to which he readily agrees, not knowing about the baby.
While searching for her sister, they find themselves dealing with betrayal, lies, and a love so deep it burns the heart.