It’s at the heart of the conflict in Casablanca, Tristan & Isolde, The English Patient, Anna Karenina, Notorious, Brief Encounter, The Painted Veil, and countless classic love stories. And yet for many readers, it’s a deal-breaker, particularly when it comes to genre romance.

As a reader and a writer, I don’t dislike infidelity or adultery plots per say. Infidelity is an uncomfortable subject but uncomfortable subjects can make for good drama. It can definitely be a challenge to give a story a happy ending after someone’s been unfaithful. Of all of the stories I mentioned at the start of the post, only Notorious has a conventional happily-ever-after ending. The others have unhappy or bittersweet endings. If the marriage survives the infidelity, you need to believe that the couple can get past it, that it won’t happen again, that the betrayed partner won’t constantly blame the unfaithful partner (which is pretty mucht he conversation Steve and Miranda have with their marriage counselor in the recent Sex & the City movie). If the unfaithful lovers end up together, one can find oneself sympathizing with the betrayed spouse. (Notorious pulls it off by making the spouse a villain, albeit a complex one who genuinely loves his wife).

Of course the terms of the marriage and the expectations go into it affect the level of betrayal. In my historical romance, Rightfully His, there’s a subplot between the heroine’s sister and her husband who have a society marriage in which both have lovers and they get along quite amiably. However, in the course of the book, they realize that they love each other and the terms of their marriage change.

I write about betrayal a lot, so when I write about infidelity, I like to explore how it compares and contrasts to other types of betrayal. In Secrets of a Lady Mélanie has undeniably betrayed Charles in a number of ways, but I deliberately left it ambiguous as to whether or not she committed adultery. I actually was explicit about it in an earlier draft of the book, then decided I wasn’t sure myself so I left it open to question. I figured out the answer for myself a bit later, and at some point, when appropriate, I’ll work it into a subsequent book.

They do confront the issue of infidelity and their different expectations going into marriage, in a scene in The Mask of Night:

You didn’t intend to be faithful when you married me.”
She regarded him with that scouring honesty with which she confronted uncomfortable questions. “No, I didn’t. But then I’d never hold my own behavior up as a model of anything.” She smoothed a crease from her skirt. “Did you? Intend to be faithful?”
“Yes, as it happens. But it was hardly as though I had a very active career to abandon.”
“And you take your promises seriously.” In the warm wash of candlelight, Mélanie’s gaze had the bruised look he remembered from last night. “Fidelity hasn’t been a word in my vocabulary for a long time. It might have been once. When I was a girl playing Juliet in my father’s theatre company. Before—”
“Everything else.” Before she’d been raped by a gang of British soldiers, seen her father and sister killed, been left penniless and homeless.
“Being raped was the least of it,” she said, in the low, rough voice he’d learned to recognize from moments when she dredged up long-buried truths. “I could have got past that, I think. It was losing everyone I cared about, fighting for survival. I had to claw my way back to a sense of purpose. When I did, so much I’d used to value didn’t make sense anymore.”
“There’s more than one kind of fidelity, Mel. You’ve been remarkably faithful to a number of things.”
Her gaze fastened on his face. “Charles, you know that I—“
He looked into the scarred, beautiful eyes from which he’d never been able to hide things. He found he didn’t want a declaration based on duty or guilt. “I know you,” he said.

How do you feel about infidelity in books? Is it a deal-breaker? If not, what you think makes it work in some stories? Does it make a difference whether it’s the hero or the heroine who is unfaithful? What the terms of the marriage are? Whether it’s a story about a couple overcoming one or both partners’ infidelity or the story of a pair of unfaithful lovers? Do you think Mélanie was unfaithful to Charles after they married? Why or why not?

I just posted a new Fraser Correspondence addition, Mélanie writing to Simon about the love affairs at the Congress of Vienna (where fidelity appears to have been in short supply).