Shape-Changer's Wife by Sharon Shinn
Aubrey was a student, gifted in the fine art of wizardry. But the more knowledge he acquired, the more he wanted to learn. So he travelled to a faraway land in search of the greatest master of all, the powerful shape-changer Glyrenden. From him, Aubrey expected to discover the secret of long-lost spells and the mysteries of arcane magic. But there was one discovery he never expected, one mystery he risked everything to solve. Her name was Lilith.

This is not a long book and I read it in one evening. Shinn has a way with words so you feel that you are almost there like a fly on the wall.