Ookami no Hanayome

Louie, the sixth prince born from an affair between the king and a maid, has a secret he can't tell anyone. Suddenly, he is sent off by the king to be married to someone in a foreign land as a "princess," being promised that his mother will be safe only if things go smoothly. The kingdom he is being sent to is the neighboring kingdom, where people live in harmony with wolves. However, the evening the ceremony is finished, Louie's new "mate" Prince Zeth soon discovers that he is not the princess he was said to be... now begins a new story in the kingdom of wolves!

(Source: Frontier Works)