In "My Boyfriend Found Out My Secret and Left Me," the narrator reveals that she had been hiding a significant secret from her boyfriend, which she feared would change how he felt about her. When he eventually discovers this secret, his reaction is one of shock and disappointment, leading to their breakup. The story explores the narrator's feelings of betrayal and heartbreak, as well as her struggle to cope with the loss of their relationship while grappling with the consequences of her secret. Ultimately, it reflects on themes of honesty, vulnerability, and the challenges of maintaining relationships.