Maelstrom by Susanna Strom

As our band of survivors flee the city, we cling to one hope: Danger lies behind us, not ahead.

Kenzie Dunwitty is one of the lucky ones. She survived the flu that ravaged the planet, but her old familiar world is shattered. Most of the population is dead, and the institutions that hold society together have been wiped out. The love she’s found with Ripper—her bad boy biker—is more than a source of comfort. His unshakable confidence in her gives her the courage to learn how to fight for survival. And to act out her wildest fantasies.
Ripper Solis will do anything to protect Kenzie. Taking care of a woman is a new role for the hardened former soldier, a role as intoxicating as she is. But even his formidable skills might not be enough to keep her from harm.
They have their eyes on the prize: Valhalla, a cattle ranch “at the ass end of nowhere.” A place so far off the beaten path that he hopes they’ll be safe. But new threats await, and they might be even deadlier than the virus.