Suterare Reijou ga Akogare no Saishou-sama ni Ikioi de Kekkon Shite Kudasai to Onegai Shitara Gyaku ni Kyuukon Saremashita

Stella, the daughter of a count, underwent rigorous training to become a queen for 10 years, but her engagement was suddenly called off when the crown prince changed his mind. Not caring about anything anymore, Stella impulsively proposes marriage to Ludovic, the prime minister 20 years her senior and whom she admires. To her surprise, he proposes to her instead! A doting age-gap love story between a young woman and a man she secretly adores! (Source: Kadokwa, translated)