This is Not the End by Sidney Bell

Zacary Trevor is the love of Anya Alexander’s life. Their sometimes tumultuous marriage has survived ups, downs, and all the in-betweens. With successful careers, a lovely home, and a beautiful child, domestic bliss is a hard-earned reality for two people whose hedonistic days are in the not-so-distant past. They’re happy. Enter Zac’s best friend, the deeply reserved Cal Keller.

Zac’s friendship with Cal is the foundation of his career and—until Anya and their son came along—the most important relationship of his life. Cal’s a cipher, someone Anya can’t help but gravitate to, even if they don’t always get along. Even more, she’s drawn to the Zac she sees when he’s with Cal—a careful, cautious version of her husband, someone with hidden thoughts and desires kept secret even from her. Inviting Cal into their home, deeper into their life, is a risk.

Zac should say no. He knows he should. But he doesn’t. From the first, the hint at the life the three of them could have together is exhilarating. And finding a new definition for family just might be worth the risk to every bond that exists between them.