Trench Tactics by Dalia Davies

Falling in love is a variable none of us can control.

When Jessica Ardem is offered an impossible to obtain round trip ticket to Isia, she jumps at the chance to finally study some of the planet’s fauna in person. After all, how can a xenobiologist do her job when she’s stuck on Earth?
But when she arrives and is delivered to the Sian man studying the deadly creatures that roam the Shadow Zone, all of her priorities shift. Learning about the man she’s getting far too close to could break her heart if she doesn’t want to break the terms of her contract.
Trench applied for a bondmate once. It went badly enough he swore he’d never try again. An outpost full of dead things is no place for a human woman. Until the Saints send him one who fits too perfectly.
Jessica attacks their problem in ways that fascinate him, but she’s going back to Earth at the end of her three month contract. He can’t keep her, but maybe they can pretend for what little time they have.

There’s nothing imaginary about what he feels for her.
There’s nothing make-believe about the way she reacts to him.
They’re both smart enough to know giving into their desires is guaranteed to end badly, but some needs defy logic.