Free from Wild Wolf Publishing: Moon Bumps
by James Marsden.
Can time, space or even the world’s end separate something that was meant to be?
When Reclamation Officer Alli Katalli finds herself catapulted away from her life, her world and her fiancé, Jon, to the long-ago destroyed planet Earth, she faces more than just a few hundred years worth of time-difference to return home.
Believing her gone for good, Jon’s life spirals out of control as he struggles to let go of his feelings for Alli. As they battle individually to survive their separation, will those who endeavor to keep them apart succeed, or is the couples’ bond just too great?
A quirky offbeat story of love, time travel and the end of the world.
Although the description sounds like a romance, it's not categorized as one. The main part of the book may be what happens while they are separated.