What is the one where 2 high school girls are together secretly but on catches the other kissing her step brother when she comes back to revive her phone from the other girls place

The plot you’re describing sounds similar to themes found in LGBTQ+ romantic dramas or coming-of-age films, but it closely resembles the storyline of the film *"The Half of It"* (2020). In this film, a shy, introverted student named Ellie helps a jock woo a girl she secretly loves, and complex feelings and relationships unfold. However, if you're referring to a more specific title or another piece of media, please provide more details, and I'll do my best to help you identify it!