In Psychology, “Limerence” is a one-sided emotional state characterized by obsessive focus on a limerence object (LO) and intense emotional fluctuations, often disrupting daily life and mental well-being. We have found many research papers suggest that limerence shares similarities with obsessive-compulsive disorder and addiction. Based on these findings, we identified new opportunities from these studies, adopted the Transtheoretical Model (TTM) as our theoretical foundation and developed “Truth Tonic,” a Custom GPT designed to facilitate LLM-driven cognitive reappraisal, helping individuals detach from limerence and regain rationality. Truth Tonic has three features core strategies: (1) using a direct and sharp tone to challenge entrenched thought patterns, (2) providing concise responses to avoid excessive elaboration on emotional distress, and (3) mimicking social media language to enhance engagement and trust. To achieve these strategies and develop the system, we collected and analyzed discussion data from platforms like Dcard (An online social media and networking platform based in Taiwan) and PTT Bulletin Board System, extracting conversational styles and persuasion techniques to inform AI responses. Then, through prompt design, we ensured responses remained brief and direct. A post-experience survey (n = 112) evaluated user satisfaction and AI effectiveness. Results indicate that most users found the system helpful in recognizing emotional patterns, gaining clarity, and engaging in meaningful interactions. Overall, Truth Tonic shows promise as an AI-driven intervention for limerence, with future refinements focusing on adaptive tone strategies to enhance user experience and intervention efficacy.