Winter Fusion by Anna Hackett

Ex-space marine Savan Bardan survived the Galactic Wars to become the most ruthless trade negotiator in the galaxy. His planet needs energy to survive, and he’ll do anything to close the deal for the Perman fusion crystals that can provide it—even if it means seducing his beautiful, infuriating opponent, a rival icier than her planet.
Perma’s top negotiator, Brinn Fjord, lost her father when Savan delayed her planet’s Trade Guild membership years ago. She hates the handsome Rendarian and the planet he represents. She’s determined to finish the deal and get rid of him as quickly as possible, so she can celebrate the holidays.
But soon the rival negotiators are in a fight for their lives. Besieged by mysterious accidents and unforgiving weather, Brinn and Savan have no one to depend on but each other. As they put the past aside, they uncover a desire hot enough to melt ice, and Brinn discovers a secret that may keep them apart.