OMG, I'm Surrounded by Three Princes Ep. 4

Erin, a down-and-out street vendor, is betrayed by her fiancé and best friend, but no one knows that her true identity is the long-lost princess. Just when the three princes find the clues and Erin can return to the royal family, her true princess identity is claimed by her best friend. In the many subsequent dangerous situations, Prince Charles repeatedly protects Erin, causing Erin to develop a different feeling for her "brother" Charles.