Bound to the Watchers by Libby Campbell

When Radiance refuses to choose between the two men who love her, they join forces and take the decision out of her hands.

After surviving a harrowing imprisonment in her homeland, Radiance has a new and independent life in her adopted country of Icebridge. She has achieved a coveted senior military rank and now lives beside the ocean that is her lifeblood. Her secluded lighthouse home is the perfect place to keep the secrets she dares not share with anyone.
Because of her special gifts, she has sworn to never give herself to only one man. Instead, she enjoys the affections of two dominant Devmaerean officers, Ghent and Khari. She is lover to both and faithful to neither.

Then a freak storm draws her into dangerous seas to save a squadron of ships bound for Icebridge. As Radiance guides the fleet, with its royal passengers toward a safe harbor, a massive sea tornado sweeps her up. It drops her into the net of ruthless pirates, men whose raging lust is at a tipping point.
As Ghent and Khari plan her rescue, they decide there will be a change in their future with Radiance. First, she will have to present herself for a shameful punishment, as atonement for her life-threatening secrecy. Is Radiance as brave as she thinks she is?