Apparently it's My Fault That My Husband Has The Head of a Beast

Apparently it's My Fault That My Husband Has The Head of a Beast (旦那様の頭が獣なのはどうも私のせいらしい, Danna-sama no Atama ga Kemono na no wa Doumo Watashi no Sei Rashii) is a Light Novel series.

Plot
Rumor has it that Princess Rosemarie is an antisocial shut-in, but the truth is far stranger. The young princess hides from the world because of a strange condition: whenever someone expresses a negative emotion, she sees their head transform into that of a fearsome beast.

It seems there's no one in the dishonest world of courtly manners she can trust... until she meets Prince Claudio of Baltzar, whose features remain ever human. The two marry at once, but she learns too late that his human features aren't thanks to a kindly nature.

Claudio has become a very real beast, all because of Rosemarie's accidental theft of his mana many years prior! Claudio's life and future are on the line until he gets his mana back — and Rosemarie would give anything to know how to do it.

Volumes

 * Volume 1
 * Volume 2