In one day, our 13th book will be published. If someone told us that four years ago we'd be on our thirteenth book and jump-starting a new series, I'd have just laughed. Because four years ago, we were 21--about to turn 22--and we'd just finished writing a book about a female sex addict and an alcoholic. Something that sounds like a bad start to a romance, but it had touched our hearts in ways that we'd hoped would resonate with others. I was sleeping on an air mattress in Becca's dorm room,...