Craig Blankenhorn / Tribune News ServiceDominic West, left, has found a challenge in filming numerous intimate scenes on “The Affair,” which premieres Sunday.

BEVERLY HILLS — When actor Dominic West stood in a hospital with the Baltimore police witnessing a victim who’d been shot eight times, he knew he was out of his element. The Britain-born West was starring as a Baltimore detective in “The Wire” — an alien land for the man who grew up on the moors of Yorkshire.

But that wasn’t nearly as forbidding as the sex scenes he has to negotiate with two women in his latest drama, “The Affair,” premiering on Showtime on Sunday.

“This show — which is slightly closer to home — I’m a family man — but playing an American in America is really odd,” he says, above the din of the noon crowd in a hotel bar.

“And doing, at my age, all those sex scenes, it’s terrifying. It’s not a lot of fun. It’s more choreography, really.”

West plays a genial and well-meaning family man whose brood is spending their summer vacation at a seaside resort. There he meets and crashes hard for a waitress (Ruth Wilson) who is married but mourning the death of a child.

“It’s good writing because the stakes are higher,” he says, leaning back in the vinyl chair. “If the marriage is good, they’re still having good sex, both characters are well-married. He loves his children. He’s a good dad, therefore it’s a lot harder to persuade people that A, why did he do it? B, why do we like him? Why do we care? And I don’t know if people do; the jury’s out on that one.”

The story is told in “Rashomon” style: from two different view points giving it an immediacy that straight narratives lack.

Being terrified of a role is normal for him, says West, 44. “It’s an essential feeling, in a way. With a role, you have to have a spark that says, ‘Yes, I can see where this is coming from. I can understand this guy.’ But I think you also have to have a lot of fear of not coming up to the mark. I think that is essential. If you think you know the character totally, then it’s probably going to be quite boring. I’m sure of that,” he nods quickly.

“It’s easy to feel frightened in acting because it’s just a terrifying thing to do because you’re putting yourself in front of people to be judged. Every role has a challenge because you’re being judged,” he says.

His wife of four years, Catherine FitzGerald, is not bothered by his torrid love scenes. “She is cool with it. I wouldn’t be. I’d be appalled. But she’s cool because she’s right. It’s no different from any other scene really, you’re pretending, and you’re trying to give the illusion of intimacy.”

“The Affair” corroborates what most of us know, that relationships can be unhinging. And West acknowledges that those in his life have been just that. His father, who owned a plastics factory in Sheffield, and his mother, a housewife, divorced when West was in his 20s. “Had I been a lot younger it probably would’ve affected me more, but I can’t imagine how much more because it was a huge deal.

“What led up to it was a difficult thing for my parents, and I hated to see them suffer. … That thing of this unit that had always been, to me, my universe was hugely disrupted. It wasn’t caused by anything. They just grew tired of each other.”

The oldest of his five children is a 15-year-old daughter from an earlier relationship. His other four — ages 7, 6, 5 and 1 — are with Catherine. It was she who was reluctant to wed, he says.

“I was dying to get married. It was my wife who didn’t want to get married. She was still hoping she might find someone better. I finally convinced her after the third child that she was inextricably bound to me for the rest of her life,” he says with a laugh.

Though he says he’s followed “the path of least resistance,” he endured a rough start. He was 3 when he developed a serious blood disease. “I don’t remember much about it but that would’ve been probably my hardest time. We had a very bad family car crash when I was 8, my brother and sister and father nearly died. And then I went away to school at 13 and was very, very homesick.”

One of seven children, West’s grandparents paid for his education at Eton, England’s elite private school. “The thing about it was it was Eton, and that’s a very daunting place, very posh. I’d never known anyone who’d ever gone there. … It was a very big culture shock, and I was very homesick for two years. It was a great, great school, and it encouraged me to act, apart from anything else. It brought that out in me,” he says.

“There has been a pattern in my life where I’ve relished strange situations and being thrown into a group of strangers, I suppose. Whether that’s doing ‘The Wire’ or traveling to the South Pole, which I did with wounded soldiers recently. It’s been something I’ve relished because I like the challenge. I feel pretty comfortable among strangers.”

That mindset is perfect for an actor, he thinks. “Because the nature of acting is you have to become very, very into it with strangers very quickly, whether you’re doing a play or this show. In this show we’re doing a lot of intimate sex scenes with Ruth, whom I’d never met before, and Maura (Tierney), whom I’d never met before — and that’s a big challenge.”