UNDER THE TWILIGHT VEIL - J. B. Thomas - Bog

In the Four Realms, arranged marriage is strictly forbidden.
The four queendoms that form the realms have lived in relative peace for centuries, and Princess Halyna of Demeterra enjoys her mostly solitary and perfectly dull royal life. But tensions between Demeterra and Silvervale have risen as the queen of Silvervale's ambitions and thirst for power have become extreme, disrupting Halyna's quiet way of life.
When presented with an ultimatum, Halyna will have to give up everything she knows and make a life-changing choice--marry Prince Lorys of Silvervale or allow her realm to go to war.
She agrees to marry the prince, a man who is known across the realms to be as cruel and formidable as his ambitious mother, but as soon as the wedding is underway, the High Goddess of sacred vows appears before them and enacts a curse on the realms as punishment for the marriage and their families' greed. The curse is one of darkness, a veil of gray that steals away the sun. Ceaseless dusk settles over the realm, and the queens fear that the plants and animals of the realms will begin to die, and the temperature will plummet, putting their people in grave danger.
As the newly bonded pair traverses the realms trying to find answers, searching for long-forgotten oracles, and uncovering family secrets, they discover their greatest challenge is not lifting the curse but will be confronting their growing feelings for one another.