The Tainted Prize (The Struggle for Sangeya Book One‪)‬

The Twin Rulers, from an opulent mansion on the island of Sangeya, rule over their other four islands with what they consider to be benevolence. Twice a year, contests are held to choose a lifelong companion for them from those girls who live on the island of Illumina who have reached the appropriate age. Enter Celina D'Orlean whose parents have entered her into the contest. As the day of the contest arrives, Celina finds herself wondering if this is a prize worth winning.
Meanwhile, on the island of Sangeya, a former lifelong companion discovers that for her, the prize has lost its value.