Dominic West, Ruth Wilson Dominic West, Ruth Wilson

There are two sides to every story, and Showtime's provocative new drama The Affair aims to tell them both.

The series, debuting Sunday at 10/9c, uses a Roshomon-like technique to tell the stories of Noah Solloway (The Wire's Dominic West) and Alison Lockhart (Luther's Ruth Wilson), a pair who begin their titular adulterous romance during a summer in Montauk. Each person is recalling his or her version of events as part of a present-day framing device, and, naturally, there are significant differences depending on who is telling the story.

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"I'm interested in psychology and the way that people think about themselves and who they are versus who they want to be," executive producer Sarah Treem

, who developed the series with In Treatment's Hagai Levi, tells "I'm really interested in memory and the difference in the way that people remember the same situation. Sometimes [there are] real contradictions when they're remembering themselves or when other people are remembering them. We're depicting that internal conflict on the screen in the two different manifestations of the same person."Noah and Alison first meet when Noah and his wife Helen (Maura Tierney) kick off a summer vacation with their children at the restaurant where Alison works as a waitress. It's not exactly a meet-cute — and even West says that he initially had trouble understanding why his seemingly happily married character would be enticed into an affair. For Treem, the answer lies in Mating in Captivity, a book by therapist Esther Perel, who Treem says did some consulting for the show."One of the lines in the book that I put on the top of our white board in the writers' room [was] something like, 'Oftentimes people don't have affairs because they're unhappy with their spouses, they have affairs because they're unhappy with themselves,'" Treem says. "That's kind of the operating principle that we were using to rationalize the affair. It was never supposed to be anybody's fault. It was supposed to be about a man who just wasn't where he thought he was going to be at this point in his life."Indeed, Noah is a public school teacher who has just published his first book to no real fanfare. Making matters worse, his father-in-law (West's ex-Wire boss John Doman) is a bestselling author whose side (and money) Helen is a little too willing to take. "It is utterly castration, his father-in-law's success in the same field," West explains. "When you know your wife secretly prefers her dad or thinks he's a better artist, that's such a powerful niggling detail that can destroy a relationship."

Read Matt Roush's review of The Affair

Alison, meanwhile, has something much more concrete destroying her marriage to high school sweetheart Cole (Joshua Jackson): the loss of their child. "Lots of marriages don't survive the death of a child," Wilson says. "They're both dealing with it in different ways and not communicating. So, her marriage is broken and it's hard to climb back from it. She's not consciously looking [to cheat], but I think she is currently suffocated and claustrophobic in that environment and she needs a way out. She's lost everything that mattered. She needs a reason to live, and in a way Noah and the affair gives her hope of life."Adds West: "There's a certain wounded bird [quality] about her that maybe he likes. He's a teacher. He's obviously a caretaker. He's someone who likes looking after people, and I suppose he gets that subconsciously at first."While all of those reasons no doubt play a part in Noah and Alison's eventual extramarital fling, Treem insists that there is no simple answer. "It's not like you meet somebody and you're like, 'You see me completely. You know everything about me, I must be with you,'" she says. "It's something ineffable. You can't really explain it. You can go back and rationalize it, but you can't really explain why you fell in love with somebody else."But thanks to its fractured storytelling technique, both Noah and Alison do try to explain it — or at least to explain what happened between them. The question then becomes, which story is true? Which person is the unreliable narrator? "That's the brilliance of it," West says. "One of the hallmarks of good writing is that you see everyone's point of view,  that you understand why people behave like they behave." Adds Wilson: "You realize there's no one objective truth. Every version of events is told through the eyes of the individual."

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Treem goes one step further. "In my mind they are both reliable narrators," she says. "To me they're both right. I believe that there are two sides of one story and both sides are true."

Ultimately, it may not be up to the viewers to decide who's telling the truth or not. (A juicy twist in the aforementioned framing device is perhaps the show's best hook.) But before whatever final truth is eventually revealed, Treem & Co. are much more interested in exploring marriage in and of itself.

"I think the statement I'm trying to make is marriage is hard," Treem says. "We go into it with these romantic notions because we have to in order to marry somebody else and promise fidelity for the rest of our lives. At a certain point in everybody's marriage, things get very complicated, choices get made, and every marriage sort of ends. Even if you stay together for your entire life, it's in a radically different place than it started."

So, is the show romantic or cynical? "For me it's neither," Treem says. "I'm hoping that it's very honest. There are some moments that are incredibly romantic and there are some moments that are really painful. I'm just trying to write a true love story."

The Affair premieres Sunday at 10/9c on Showtime.

(Full disclosure: is owned by CBS, Showtime's parent company.)