I Abandoned My Engagement Because My Sister is a Tragic Heroine, but Somehow I Became Entangled with a Righteous Prince (Manga) Vol. 1

Leia, a saint of the Kingdom of Elshaid, has her happily-ever-after shattered when her "tragic heroine" of a younger sister accuses her of abuse. Believing the lies, Leia's fiance breaks off their engagement, leaving her despondent. But a surprise encounter with the crown prince changes everything. Charming and righteous, Prince Erik is determined to discover the truth about Leia's character by having her come live with him in the royal palace?!