Romance Fantasy Heroine is married as revenge but not what is expected by hero

[Romance]

Read around January this year I think. Heroine was last born child and her mother diedshortly after her birth. She and her sibblings are named after the seasons, Spring, Summer, Fall, I believe she was Winter. But her father can't stand her and has her live in a tower away from view. One day a king rides in demanding to marry one of the kings daughters. The king tricks him and marries him to Winter, but before the wedding he whips winter. They marry and the king is eager to get home and is upset by being deceive, having believed he married one of the other sibblings. On the trail home her back opens up and she is in pain. At his kingdom she tries hard and is not accepted. There is a lot of deceit. He saves her life more than once and is known as an Ice king, with a darkness eating him inside. A woman betrays him and brings the ice king alive back inside of him. She has to get help from others. The end battle she has an ancient spear that would kill him and the darkness inside him, but she manages to see a glimpse of him and steps in front of the spear, and he comes back realizing whats happened, finally they get a happy ending.

[Kris]

Romance, is this book for adults or teens?

Link for Sherry's suggestion - The Winter King by C.L. Wilson