Once upon a time, you promised to love for better or for worse. And so, through sickness and health, you tried your best in your marriage. Maybe that worked. Maybe it didn’t. Maybe you got the relationship you dreamed about, but in the new novel, “The Perfect Marriage” by Kimberla Lawson Roby, desires outside this household are stronger than the ones inside it. Denise Shaw had everything she’d ever wanted. She had a very-well-paying job she loved. Her adoring, handsome husband, Derrek, who’d come from a broken home with shaky roots, also had a great job with a fat salary. They had a beautiful home, fancy cars, good money saved, and a wonderful, smart daughter who was the light of their lives.