The Breeder by Lynne Silver

Twelve men are willing to fight and die for her. Only one will triumph. In a world where fertility is a rare and treasured thing, Jane—the breeder for Windy City—is ready to fulfill her destiny and repopulate the earth, with the help of the one man strong enough to have her. The man she’s dreamed of for as long as she can remember. One fight. One winner. One month of uninhibited pleasure.

For Ethan, losing Jane isn’t an option. He’s spent years preparing for this battle, for his woman, but marriage and family are a thing of the past, and happily-ever-afters don’t come easy. No matter the temptation, they can’t stay lost in each other’s bodies forever. The clock is ticking, and Ethan means to keep Jane for always. No matter what it takes.