What's Up Fox? (2006)

The boy next door returns from his around the world stint as a grown man. She's known him his whole life and treats him like a big sister but struggles with a new attraction to him. One drunken night they sleep together. He wants to date her but she refuses. His struggle is to get her to see him as a man. Her struggle is whether she is should risk family and society's disapproval and dating a younger man.