From the moment they met as first-year students in college, Gillian Carlisle and Mike Russo became as thick as thieves. On paper, they made zero sense. She, an upper-class girl whose nose was always in a book. He, a lower middle-class jock with a love for football and a head for numbers. Despite their obvious differences, they clicked, and their bond grew stronger with each passing year. Everyone in their lives assumed they would pair off at some point and settle down. No one ever believed them when they swore they were best friends and nothing more.After decades of nursing each other through failed relationships and broken hearts, they opt for the comfort and security of cherished friendship over the notion of romantic love by making a pact to marry if they're still single by age 40. Now, both successful in their chosen careers, they settle very happily into their unique brand of couplehood—living half of the year in New York City, where Mike runs a successful brokerage firm, and the other half in the Cotswolds, where Gillian pens biographies of British noblewomen.Gillian’s latest pursuit requires an expert in medieval military history. To that end, her publisher aligns her with Dr. Simon Hicks, a historian of some notable acclaim, who partners with Gillian to write the history of one of England’s famed warrior queens. The pairing is a success on a professional level; and the two become fast friends. But certain aspects of Simon’s past make forging this new relationship a challenge he’s not sure he’s up to facing.It’s been years since Simon was jilted in the cruelest of ways, yet no matter how much time as passed, he remains unwilling to open his heart to love again. That is, until Gillian comes into his life. She’s his ideal in every possible way, except for the unfortunate fact that she’s not free to love him in return. What Simon doesn’t know, however, is that Gillian is also grappling with her own dilemma, which throws her perfectly ordered life off kilter. Faced with an impossible choice, she must consider where true happiness resides…and if she’s brave enough to risk everything to find it.Happenstance is an introspective journey about loyalty and betrayal; love and loss; and whether choosing one’s own happiness is either an act of selfishness or a path to self-discovery.