Karak Contact by Ruby Ryan

Where did you come from, Eric?

A mysterious satellite crash. A late-night car accident. And a stranger who looks shockingly identical to the man on the front of Joanna’s book.
After hitting Eric with her truck in the middle of the Wyoming wilderness, Joanna has no choice but to take him back to her cabin. But his wounds heal suspiciously fast, and she begins to suspect his concussion is covering up some deeper secret.
She never would have guessed the truth.

When she discovers the man she’s taken to bed is actually Arix, a shapeshifter alien from the Karak Dominion of Planets, it’s all she can do not to run away in terror. But UFO hunters who witnessed the spacecraft crash begin snooping around her cabin, forcing Joanna and Arix to find a solution that keeps them both safe—which leads to them making an impossible, and downright crazy, decision.