The Girl in the Tower by Katherine Arden
Sequel to The Bear and the Nightingale, this story takes up where the first book ended: Vasya has left her family and her village. Together, she and her marvelous horse (with some help from Morozko, the frost demon) journey towards Moscow, and (of course) things go terribly wrong along the way.
Familiarity with Russian folklore will definitely aid in understanding and enjoying this dense, dark tale. Vasilisa and Morozko figure in many traditional stories, as do...oh, but that would be a spoiler.
If you know the stories, you may recognize characters along the way; otherwise, you will be as surprised as Vasya herself when true identities are revealed.
Some kissing, some bloodshed, some nekkidness, some demons and devils, and quite a lot of magic. This is second in a trilogy, but does not end on a cliffhanger.
Highly recommended reading for cold, blustery nights when the fire is ticking in the stove, and winter is just on the other side of the wall. Ages 12 to adult.