First off,, I am not a fan of cheating so this books loses points on that alone.
We have like a lot of regency stories about a young girl being married off to a slightly older guy against his will who then insults her and takes off for the continent. The fathers made these arrangements to settle a gambling debt. So I can understand the Dukes heir being a little upset. From there on I find our "hero" Adam to be heartless, judgmental, arrogant, spoiled, unreasonable, narcisstic..pardon my spelling lol. and uses any excuse he can to run back to his mistress and embarrass his young wife. It was to late to redeem him for me. Allegra his wife, has built her life in the ton. She is loved for her beauty and kindness. She is flirtatious but innocent. Adam who brings back his French whore mistress who has made him believe she is an innocent widow plots to get rid of his wife to marry him. He buys her a house and continues to sleep with her throughout the book as the mistresses scheming with others to tear down his wife"s character works. As Adam finally decides to divorce his cheating wife and have her followed because of all the poison that has been whispered in his ear. It does have a HEA...but I would have told the new Duke to stick it where the sun don't shine.