In Good Time by Tricia O’Malley

It’s time to remove her crown.
Aurora was raised to lead, with the expectation that she will one day become ruler of the Mer of Triste Island. There’s just one problem. Nobody’s bothered to ask Aurora if she wants to be queen. Chafing at the confines of her role, Aurora risks everything for a chance at a new life. Ready for adventure, Aurora washes up on Siren Island at the feet of one very bewildered video-game designer. The clock is ticking before the Royal guards find her, and Aurora is determined to experience everything that life on Siren Island can offer.

Including Nathan.
Nathan can’t believe his eyes when the most gorgeous woman he’s ever seen in real life walks out of the ocean and asks him for a kiss. From the moment he meets Aurora, his life is turned upside down. Painfully shy, with a heart of gold, Nathan finds himself torn between falling for Aurora and protecting the seemingly naive beauty.
It isn’t long before her past comes calling, and Aurora is forced to make a choice between her people and the only man who has ever seen her for who she truly is. Can she have it all–or will Aurora choose duty over love?