Crossing the Line (Alpha One, 1) by April Andrews
In the year 2152 the last of humanity lives on a series of generational spaceships. Twice a year, on the ship known as Alpha One, five scouts are chosen to head out into deep space and find places where Alpha One can re-stock its supplies.
Tobias Hark, newly qualified pilot, is one of those scouts but Tobias isn’t being sent on his mission alone. He has been paired with his commanding officer, Javier De Santos. Javier also happens to be the one man that Tobias has been crushing on ever since he joined the pilot unit. But there are rules on Alpha One and those rules mean that Tobias can never let his superior officer know how he feels.
Javier has been following those rules too, despite the fact that he has lusted after Tobias from the day they met. But when their ship lands on a strange planet, and they have to make some drastic decisions in order to survive, Javier soon realizes that if there is ever a time to break those rules it is now. Because protecting Tobias has just become his priority and the only way that Javier can do that is by crossing the line.