The Wife Between Us by Greer Hendricks and Sarah Pekkanen

Nellie, a young teacher, has met the man of her dreams. Nine years her senior, Richard is charming, handsome, and wealthy. He pampers Nellie like a queen--until he doesn't. Nellie is constantly thrown off-kilter--is Richard manipulating things that happen between them? Reality and deception are woven into a strange pattern of twisted understanding. As the difference in how each perceives their marriage grows wider, so does their estrangement until Richard leaves Nellie for another woman. Or so everyone believes. Who is this younger, blonde version of herself? Nellie is compelled to stalk her around Manhattan like a jealous ex. Will this woman become her replacement? Read a sample.