Jude knows he isn't relationship material. The entire population of Mars made it abundantly clear he's damaged goods, and he agrees. His issues are why he works a remote job flying around the galaxy prospecting for metals, and why he ruthlessly quashes any feelings for Cal, his surveying partner.
Cal has been looking for an opening to suggest he and Jude could be more than friendly coworkers. When they crash on a tundra planet, the men have a lot of free time, and they put it to good use having sex. It's fun, but Cal wants Jude as a boyfriend, not a friend with benefits.
Marooned on a hostile world, with Jude's demons rearing their heads, Cal's first task is to keep the two of them alive. His second is to convince Jude that, no matter how much he's suffered, romance can still be in the cards.