On the day I proposed to my beloved girlfriend, I discovered she was already married—I decided to use unprotected sex until she died, completely destroying our marriage—. Kitagawa Haruka JUR-657

I've been dating my girlfriend, Haruka, who's three years older than me and shares similar interests, for about three years. I've decided to propose to her on our next meeting, but there are many mysteries surrounding her. We always meet in my room, only during the day on weekdays, we've never spent the night together, and I don't know where she lives... On the day of the proposal, I discover that Haruka is married. After being told I can't marry her... I'm determined to destroy everything she has...