Just One Day by Gayle Forman

When sheltered American good girl Allyson “LuLu” Healey first meets laid-back Dutch actor Willem De Ruiter at an underground performance of Twelfth Night in England, there’s an undeniable spark. After just one day together, that spark bursts into a flame, or so it seems to Allyson, until the following morning, when she wakes up after a whirlwind day in Paris to discover that Willem has left. Over the next year, Allyson embarks on a journey to come to terms with the narrow confines of her life, and through Shakespeare, travel, and a quest for her almost-true-love, to break free of those confines.