IT is the week of Valentine's Day and a scent of scandal is in the air.

Nicholas Sparks, the author who is to love stories what John Grisham is to legal thrillers, is on tour with Safe Haven, the eighth of his 16 novels to be made into a film.

He has been in Los Angeles, Dallas, and now he is on the line from New York. By my calculations, he will struggle to make it home to his wife in North Carolina for Valentine's Day. Okay, it is not exactly who killed JFK, but when you have sold nearly 80 million books on the back of being the emperor of lurve stories, missing Valentine's Day is something of a big deal.

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But the deal is off sooner than you can say hold the book section's front page. Sparks will indeed make it home, albeit not till 9-ish. But I bet he has forgotten to send flowers? "I've already arranged for flowers." Is that all? No. As a surprise, he is sending his wife wine as well. Wine she likes, but she doesn't know he knows she likes it.

"We were at dinner with a group of friends a few weeks ago and she really liked this glass of wine she had. So I got the name of it and placed an order."

Clearly, it does not do to underestimate Mr Sparks. His novels might provide escapism for millions, but he is not a head in the clouds sort. Behind the soft focus, sun-dappled covers of his books is a sharp business brain, one that has successfully navigated books and cinema and is now moving into television.

Safe Haven stars Julianne Hough and Josh Duhamel in the story of a young woman who moves to a tiny coastal town to start a new life. Also putting the pieces together again is Duhamel's widower. They become friends and, well, you know how it goes from there. Not this time, though. With a harder edge than his previous works, Safe Haven is something of a departure for Sparks.

"It's probably more of a romantic thriller than simply a romantic drama," says Sparks, 47. As to whether he will continue down this road, he is keeping his counsel.

"Whenever you try to write a story you've got to insert some conflict into the relationship, otherwise it's frankly a boring story. There's got to be something. Every great love story has some conflict. It doesn't matter how far you go back in time, it's just part and parcel of the genre. The goal for me is to try to keep those conflicts as fresh and original as I possibly can."

Like all of Sparks's novels, Safe Haven is set in North Carolina, where he lives with Cathy, his wife of 24 years, and their five children. The area gives a homely feel to the books, and a glossy, calendar-pretty look to the films.

"The American South just looks different from a lot of other places, and it lends itself well to these kinds of stories because the coasts are dotted with these small towns where community is still really important, and family and friends and neighbours and faith – all of these things play a role. Then you add to it the geography of these wide, slow-moving rivers and trees draped in Spanish moss."

And, of course, it doesn't rain on love's parade a lot. For that reason, I'm assuming, he would never set a story in Scotland, which he visited last August on holiday, staying at Skibo Castle and touring the Highlands.

"I've learned never to say never," he laughs. "I certainly could have characters from Scotland, or they could go to Scotland."

Sparks studied business finance at university, wrote his first novel at the age of 19, then another at 22. At 28, after a succession of jobs, including one selling pharmaceuticals, he wrote what was to be his first published novel, The Notebook, which he sold for $1m. He chose love stories, he says on his website, because "there was little to no competition".

His website, on which he describes how he broke into print, is a must-read for any aspiring author. Sparks has gone one better in encouraging writers, funding creative writing scholarships at a local university. His foundation also gives money – almost $10 million, estimates the website – to good causes, including research into childhood diseases, animal rescue organisations, and education. "I just think it's the right thing to do," he says of his philanthropy.

As his best-selling status testifies, Sparks is not short of fans (among them is Hough, who grew up reading his books). A typical message from one reader said she loved his books because they gave her hope that there were nice guys out there.

"I've heard a lot of different reasons over the years," says Sparks on why his books have such a following. "I'm just glad there are those out there who do enjoy them, for whatever reason they choose."

Not everyone shares that enjoyment, of course. Film critics appear to be especially resistant to the allure. One described The Notebook as "a cloying weepie in which senile dementia meets Mills and Boon". "Formulaic", "treacly", and "maudlin" are among other responses to the movies.

Sparks could wave his bank balance in response, or direct critics to some of the stars that have appeared in the movies, among them Ryan "hippest man in Hollywood" Gosling (The Notebook), and Channing "cool enough for Soderbergh" Tatum (Dear John).

Instead, he takes the diplomatic tack. "What I can say is that I'm proud of the novels that I've written, I did my very best when writing them, and I'm perfectly willing to admit that there will be those in the world who don't like them. I'm okay with that."

With three television shows now in development he is entering a new sort of business, one where success is not guaranteed. "If I write a novel there's a 100% chance it will get published. Not so in television. If you run 25% it's very successful."

Still, Sparks is a stayer. He has stayed with writing, he has stayed with keeping fit: a track and field scholarship paid his way through college, and he coached a local team. He has even stayed with his old university subject, business finance, reading books on economics as a hobby. "Perhaps there's something to be said for exercising both sides of your brain to enhance overall creativity."

He travels 100 days a year promoting the books, giving readings and talks, and taking part in signing sessions. "It's just part and parcel with the other side of this business." Even with the move into television production, he will still write novels. It would be tough to imagine stopping, he says. "I'm sure I'll continue to pursue that craft and at the same time I may pursue other things. I think that a full life is a good life, and I try to keep a full life."

Safe Haven by Nicholas Sparks is published by Sphere, £7.99. The film opens on March 1.