Daisuki datta Konyakusha ni Miryou no Mahou no Sei de Konyaku Hakisaremashita.

Sienna loved her fiancé, the second prince Riley, ever since she was a little girl. She was looking forward to being a happy bride... However, Riley suddenly and coldly tells Sienna, "I'm breaking off our engagement." Next to him was the lady Imogene, who was also in love with Riley. He says that he had found true love with her. Sienna is shocked, and when Imogene flashes the ring on her finger, Riley becomes even more enamored with her... A handsome prince whose heart has been stolen away and an innocent noble lady. What will become of their sweet, passionate love? (Source: Kurofune Pixiv, translated) Note: Includes two extra chapters.