The Billionaire's Assistant: A Billionaire Romance Series. The Sons of Sin, #7

Max Lane is about to turn thirty and to settle down is in the forefront of his mind. His taste in women doesn't make his choices in finding a wife and future mother of his children easy. Wealthy, gorgeous women with long legs and luscious bodies are great until you have to deal with their entitled attitudes, which is something the young billionaire neither has nor finds attractive. Alexis Mathews is a freelance accountant who comes into Max's life just as he's ready to make some changes to it. Initially, he takes her on as a project but soon realizes he'd like to keep her for himself. Alexis' long time insecurities make it hard for her to believe she's the right girl for a man of Max's wealth.