When You Were Mine is a 2012 young adult novel by American author Rebecca Serle. It presents a contemporary reimagining of William Shakespeare's classic tragedy Romeo and Juliet, told from the perspective of Rosaline, a character who is mentioned but never appears in the original play. The narrative transplants the star-crossed lovers into a modern American high school setting, where Rosaline Caplet is a senior whose life is upended when her cousin Juliet returns from abroad and immediately catches the eye of Rob Monteg, Rosaline's longtime crush and secret boyfriend.
The novel explores themes of love, betrayal, and self-discovery as Rosaline navigates the fallout of losing Rob to Juliet. Serle's debut work was praised for its witty voice and for giving agency to a traditionally overlooked female character. By centering Rosaline's experience, the book offers a fresh take on a familiar story, examining what happens to the girl who was left behind in one of literature's most famous love triangles.
When You Were Mine became a bestseller and helped establish Serle as a prominent voice in young adult fiction. Its clever premise of revisiting a canonical work from a marginalized character's viewpoint resonated with readers and critics alike, eventually attracting interest for a screen adaptation.