Yomei Wazuka no Intai Seijo wa Reikoku Koushaku to no Yakkaibarai Kon wo Ouka Shitai!

Saint Muriel has sacrificed her life and exerted all her strength to expel the miasma that harms the kingdom. However, a selfish prince falsely accuses her, breaks off her engagement, and then tells her to retire as a saint due to the depletion of her magical powers. Disgusted, she knows she only has a short time left to live. Determined to live the rest of her life without regrets, she is arranged to marry the ruthless duke and rumored Roy Calvert, but she decides that he is better than the prince! But! Contrary to her resolve, Roy begins to dote on her...!? The reversal of the beloved life of a fired saint!

(Source: Kodansha, translated)