AI SURU HITO WA HOKA NI IRU TO ITTA OTTO GA, WATASHI WO HANASHITE KUREMASEN

"Where is my destined bride...?" Countess Seraphina, who lost her parents at a young age and has since taken on the duties of the lord in place of her younger brother, finds herself in a predicament at a ball when she saves Duke Maynard from a difficult situation. This leads to a contract marriage between the two. However, Maynard suddenly declares, "I have someone I love..."? (Source: Ichijinsha, translated) — Description from AniList community (anilist.co).