Hatsukoi no Hito to no Hare no Hi ni Reijou wa Uragiri wo Shiru: Shiawase ni Naritai node Koushaku-sama no Kyuukon ni Damasaremasen

Titianne was dumped by her ex-fiancé because she was a knight. But then, the Duke whom she admired proposed to her! However, on the day of her wedding, she hears that the Duke has a lover... "I'll be happy with a nice man too!" While Titianne, who vowed to escape from her own wedding, makes plans to find true love elsewhere, the Duke doesn't seem to want to give up on marrying her, saying, "I won't allow other men to lay a finger on her." (Source: Kadokawa, translated)