Secrets of a Song. The Falling Kingdoms, #5

A disgraced princess. A cursed prince. A prophecy that could drown them both. The islands of Sheema are sinking. Slowly, relentlessly, the sea creeps in-and with it, the echo of prophecy: Should the crown prince succumb to love, the sea shall reclaim its kingdom. Prince Damien was never meant to rule. Gifted with powerful lamia magic that bends hearts and clouds truths, he was raised to serve as consort to the Empress.
Now that the empire is no more, he carries the weight of his father's throne and a curse that makes every relationship suspect, every moment of joy dangerous. For him, love is forbidden-for the safety of his people, and the survival of his soul. Odessa Chrysos once wore a crown and nearly burned an empire to the ground. Exiled, broken, and haunted by her mistakes, she's content to wither away in solitude.
Until Damien shows up on her crumbling doorstep. Infuriating. Impossible. And offering her something she no longer deserves: a future. Bound by duty and scarred by their past, they should be enemies. But as ancient magics rise, dragons stir, and the kingdom begins to sink, Damien and Odessa find themselves drawn to each other in ways neither can afford. Because love might be the death of them all. Set in a world of sinking cities and a maze of canals, with dragonkind unlike any we've seen before, Secrets of a Song is a sweeping tale of redemption, reluctant alliances, and the fine line between love and utter ruin.