The Serpent and the Wolf.

"The Serpent and the Wolf" by Rebecca Robinson is a captivating debut romantasy novel that combines mysterious magic and a tense political marriage. Princess Vaasa Kozár inherits dark magic that caused her mother's death and is married off to a neighboring ruler by her ruthless brother. Unaware of her lack of consent, Reid Cazden, her new husband, offers her a deal to help tame her magic in exchange for staying married for three years. The slow-burn romance between Reid and Vaasa, along with their witty banter, takes center stage, and the nail-biting conclusion sets the stage for a potential sequel. [Extracted from the article]