Tarnished Crown (The Lochlann Feuds) by Robin D. Mahle

I was finally going to do something right. Marry for love and for my kingdom. Keep my people safe. That was the plan. Then an archaic law tore everything apart and bound me to the most feared man in all of Socair. Evander treats me like a pawn, calls me his pet, and holds my future in his bloodstained hands. But when enemies strike from the shadows and loyalties fracture, I start to realize the awful truth: being his might be the only thing keeping me alive. I owe a blood debt to Bear. A debt I have to pay… even if it costs me Theo. Even if it breaks my heart.