It is a book in which a girl has the power to change the color of others and other things, except herself. She goes on a journey with this guy to save her family (?) and I remember they get lost in a forest. There’s this huge contest to determine her skill in this town, and she gets a 0.
I do remember the cover art; which shows the girl, who has white hair and white skin, and the boy, who has white hair but a tan skin tone. The girl has a red traditional dress on, and the boy has a blue grey hoodie. The background color of the cover is red.