Nisemono dato Tekikoku ni Tsuihou saremashita ga, Douyara Honmono no Seijo wa Watashi no You desu.

Amaryllis is called the "Ice Saint" for her expressionless face, and she has long been mistreated by her fiancé, Crown Prince Nate, and her stepsister Carla. Even so, she devotes herself to her duties as a saint for the sake of the people—until Nate and Carla frame her and cast her out with the words "Get out, you fake saint," exiling her to the enemy Kingdom of Rise. Worse still, Nate's scheming leaves her abandoned in a monster-infested wilderness on the way there. The one who saves her from certain death is Victor, renowned as the greatest genius mage in the Kingdom of Rise. Surely no one would welcome a saint from a hostile nation... or so Amaryllis believes—until she is met with a reception far warmer than she ever imagined! A doting romantic fantasy about a girl called the Ice Saint who unlocks her hidden talents and seizes her own happiness!

(Source: Funguild)