"Reincarnated as the Crown Prince who Broke the Engagement"

As the plot dictated, I would someday break my engagement with my fiancee lady Shaina De Brause, the daughter of a prominent duke. If my fiancee wasn't a reincarnator, she would die and I would end up being tortured and killed by her childhood friend Gideon Clayden. If she was, she would gladly accept the breaking of our engagement, found her true love with Gideon, while I would have a bad ending with the heroine.

Only bad end was left for me. A story needed a spice to make it more entertaining and I'm supposed to be that factor. What a prized luck.