The Inevitable Singularity (Paladins of the Republic Book 1) by Molly J. Bragg

Sean, a mercenary, is the bodyguard of Grand Master Caila of the Order of the Paladins of the Republic. A fact that the entire Order, except for Caila herself, resents deeply since they kicked Sean out almost twenty years earlier. It doesn’t help matters that Caila has taken a vow of Celibacy, but everyone knows that she and Sean have feelings for each other. Sean’s presence is only tolerated because Caila is the official Seer of the Paladin Order. While all Paladins can see the future to a limited extent, Caila’s gift with foresight exceeds even the head of the order. But when a mine destroys Caila’s ship just as they arrive in the Ptolemy system to settle a dispute over a hyperspace route, it quickly becomes clear that someone doesn’t want their mission to succeed. With only Reagan, a Paladin with a personal grudge against Sean for support, Sean and Caila make their way to Ptolemy, recruiting allies along the way. But each time they look into the future, Caila sees a vision showing her that Ptolemy will be reduced to a lifeless cinder if they leave, and Sean receives a warning that Caila will die if they stay. Can they avoid disaster, or will Caila be forced to sacrifice herself to save an entire world?