Forever... by Judy Blume
This novel follows the story of Katherine, a high school senior, as she navigates her first serious romantic relationship with a boy named Michael. The two fall in love and, after dealing with the complexities of intimacy and the pressures of their peers, they decide to take their relationship to the next level by becoming sexually active. The book explores the emotional and physical aspects of their relationship, the consequences of their decisions, and the reality that first love doesn't always last forever.