Furman, W., & Shaffer, L. (2003). The role of romantic relationships in the lives of adolescents. Journal of Adolescent Research, 18(2), 131-154.
The transition from "classmate" to "romantic interest" usually happens in the quiet corridors of middle school or the early years of high. This is the classic "Slow Burn" trope in real life. It begins with a shift in perspective—suddenly, the person who has been a background character in your life for six years moves into the foreground. The romantic storylines here are often characterized by: The Shared Milestone:
Middle school is the definitive turning point for school relationships. This is where biological changes meet social pressure, creating intense, albeit often short-lived, romantic storylines.