The Gifting. The Star Girl Series, #2

Her world had sent her into space to die. Now it wants her back to make sure she does. Six months after Sah'Reena's arrival, a strange object crash lands on Earth. A device she's positive came from her home planet, Murrall. At the same time, NASA scientists discover a strange new body orbiting the sun exactly opposite of Earth. It's only when a Deathship appears close to the Johnson Space Center in Houston that she and Robin learn the truth: Murrall was caught up in the same anomaly as her space pod, and has been brought into this solar system.
Once again her life is in jeopardy as her planet wants her back to fulfill the original death sentence placed upon her. But when Robin travels back to Murrall to present himself as her true mate, and to ask them to spare her life, they witness the horrible devastation caused when the planet was ripped from its galaxy. Knowing it may be his only chance to save the woman he loves, Robin offers a possible solution to save both Sah'Reena and her dying world.
But first, he has to prove to everyone that he and the woman he's taken to wife are compatible by undergoing a proving ceremony.  Regardless of the outcome, one man is determined to see the powerful Gifted dead, no matter what the cost.