Blake Lively (2011)
Um yeah, this is one you probably forgot about!
Before Blake was Mrs. Ryan Reynolds, the Gossip Girl star had a whirlwind romance that seemed plucked straight out of a Serena van der Woodsen plotline. Leo was 36, she was 23. They connected at the 2011 Cannes Film Festival (where they were spotted getting cozy on Steven Spielberg's yacht) and embarked on a Summer of Love tour across the globe, from France to Italy to New York to Los Angeles. They announced their breakup in October and, less than a year later, Blake said "I do" to her new leading man.