Akuyaku Reijou ga Ponkotsu Sugite, Ouji to Kon'yaku Haki ni Itarimasen

One day, Beatrix, a natural-looking marquise, suddenly announces to her maid of honor that she is going to be a villainess. What? Beatrix confesses that she will become a villainess in order to break off her engagement. What is the young lady thinking when she is betrothed to a prince whom everyone admires?