Against all odds

this is a real book and the description that I will put hear is from the back of the book called Purple Hearts By Tess Wakefield.
Cassie Salazar and Luke Morrow couldn't be more different. Sharp-witted Cassie works nights at a bar in Austin, Texas to make ends meet while pursuing her dream of becoming a singer/songwriter. Luke is an Army trainee, about to ship out for duty, who finds comfort in the unswerving discipline of service. But a chance encounter at Cassie's bar changes the course of both their lives.

Cassie is drowning in medical bills after being diagnosed with diabetes. When she runs into her old friend Frankie, now enlisted in the Army, she proposes a deal: she'll marry him in exchange for better medical insurance and they can split the increased paycheck that comes with having a "family." When Frankie declines, his attractive but frustratingly intense friend Luke volunteers to marry Cassie instead. What she doesn't know is that he has desperate reasons of his own to get married. In this unforgettable love story, Cassie and Luke must set aside their differences to make it look like a real marriage...unless, somewhere along the way, it becomes one...
this is just my take and a story on what I think could happen next based on how I understood the book and movie.