The Pursuit of Lies — Debra Burroughs

In this 4th book in the Paradise Valley Mystery series, Emily Parker, a sweet but sassy small town private eye, races to solve a scandalous murder. Her world is suddenly flipped upside down when the man she loves, the town's sexy police detective, is accused of murdering a female Assistant District Attorney, with whom the police believe he was having an affair. With the help of her close circle of friends, Emily must fight to prove him innocent.