Okubyou na Hakushaku Reijou wa Momegoto wo Nozomanai The Countess Is Timid and Doesn't Want Any Trouble

Synopsis

Amelia is a plain girl who is Sophie's fan and follower. One day, she sees Marion, Sophie's fiancé, with Rozetta, another girl. "I wonder if His Highness will look at me more if I earn Rozetta's ire..." To prevent Sophie from becoming the antagonist, Amelia begins to coach Sophie in love. However, this attracts the attention of Sophie's tsundere brother?! (Source: Kadokawa, translated)