How did Tu B’Av evolve from a public festival into a day associated with adding Torah study at night?

This source-based Hagut Yosef essay explores the question: How did Tu B’Av evolve from a public festival into a day associated with adding Torah study at night? The canonical Hebrew article develops the theme through Torah sources and reflection on human life. This localized discovery layer preserves the source’s meaning and identity and does not add new halakhic, historical, psychological, medical, legal, political, scientific, or empirical claims beyond the Hebrew source.