Marielle Clarac Series

The plain, unpopular, inconspicuous and dull wallflower of the social circles. Even so, a marriage proposal arrives for such a Mariel. The fiancé is, surprise!, the heart-throbbing imperial knight Simeon-sama! Why does he, towards this girl? Even as she is showered in jealousy and scorn, Mariel is happy. After all, Simeon-sama is the perfect delicacy, a handsome youth with a bright exterior but a dark interior! This is the story of a girl who secretly fangirls over her fiancé and his surroundings.

(Source: Ichijinsha, translated)