Vampire's Mate - Guardians, #1

Enter a realm where love is tested, fangs are bared, and destiny weaves its wicked web. Marcus is haunted by the loss of his beloved in a brutal demonic war. Resigned to a life of servitude and awaiting the curse that will claim his soul, he is shattered and closed off from the possibility of finding love again. But when divine intervention grants him a second chance, the vampire finds himself torn between his immortal existence and an unexpected human connection.
His heart yearns for her, but he can't reveal his true nature without shattering their fragile bond. Cassandra, betrayed and left at the altar, has vowed to forsake love. Her wounded heart seeks solace and a fresh start, until a seductive stranger invades her dreams, blurring the lines between fantasy and reality. Little does she know that her encounter with this dark man will thrust her into a hidden world, where immortal beings and ancient prophecies collide.
As Marcus and Cassie's paths intertwine, a malevolent force looms, threatening to claim Marcus's very soul. Caught in a perilous struggle, Cassie discovers the depths of her own courage and the extraordinary power of love. To protect Marcus, she must make a fateful choice-to forsake her mortality and embrace the immortal life that awaits her. But the consequences of her decision could be more dire than she ever imagined.