Under the Highland Moon by Juliana Wight

Only the moon can witness the truth in darkness…
Ceana discovers that her feelings for the man she has always loved are not one-sided. His protectiveness and kindness soon prove to be more than just friendly affection. Yet, unbeknown to Ceana, her Highlander withholds a secret. Torcall has always had eyes for Ceana. But the death of his parents has left his mind scarred and wounded. At all costs, he needs to control his dark side to protect her.

Their romance is soon interrupted when the bodies of young women are found brutally murdered every dawn.
And to Ceana’s surprise, by coincidence or not, Torcall is found near the murder scene, each and every time.
When the whole clan starts accusing him of abhorrent deeds, she begins to suspect him. And before Torcall can defend himself, he discovers that fate has played a nasty game on him. While Ceana needs to figure out whether Torcall is a murderer, he must prove his innocence before she becomes the next victim… Only she can help him tame the beast inside him…