Zac Efron's just proved that his charm definitely has no limit. On Monday, the actor shared a sweet message for his girlfriend, model Sami Miró, on Instagram in honour of their anniversary. In the photo, the couple, who began dating last September, is seen standing on what appears to be a hotel room balcony as Sami snaps their reflection in a glass door. Zac plants a sweet kiss on Sami's head as she leans back into him. "Happy anniversary baby :) I love you @samimiro September 5th," Zac captioned the photo. Sami also took to Instagram to share a cute photo of her and Zac, writing, "Time flies when you're having fun. Happy anniversary baby I love you too @zacefron September 5." The pair's special day comes just a few weeks after they attended their first red carpet event together. They've also shared many adorable moments together on social media.