Mattheo Riddle has spent years convincing himself that being Theodore Nott’s best friend is enough. It isn’t. Desperate to stay as close to Theo as possible, he makes a selfish decision he’ll regret forever—he starts dating Theodore’s younger sister. To everyone else, the two of you are the perfect couple. But behind every date, every kiss, and every shared holiday is a secret Mattheo can never admit: you were never the one who stole his heart. Your brother was. As your relationship deepens and genuine affection begins to blur the lines of his deception, Mattheo is forced to confront an impossible choice between the life he wants and the people he’s destined to hurt.