All was not quiet on the home front last year, offscreen or on.Tiger Woods, the golf god with a carefully manicured image, got caught cheating, followed by near-daily disclosures of an ever-growing list of mistresses. Gov. Mark Sanford lied — badly — about a rendezvous with his Argentine soulmate, then gushed about her on TV while his wife was watching. And latenight curmudgeon David Letterman was forced to confess his misdeeds after a blackmailer threatened to expose his extracurricular activities at work. That’s not all: Reality show parents Jon and Kate Gosselin stepped out on each other, and failed presidential candidate John Edwards continued to deny responsibility for his love child until almost two years after the child was born out of wedlock. Films in 2009 were certainly on topic with what was going on in these high-profile real-life relationships. Nearly every other movie released in the past six months, it seemed, dealt with cheating, whether it was a womanizing director in “Nine,” a 1960s British schoolgirl learning a painful lesson about the glamorous life in “An Education” or ex-spouses reigniting in the modern screwball comedy “It’s Complicated.” Four of the year’s best picture nominees — “Education,” “A Serious Man,” “Up in the Air” and “Precious” — grapple with infidelity of one form or another. The nommed pics vary greatly in mood and setting, but cheating is pivotal to all four. Tellingly, the heroes or heroines of the movies are each unwitting or unwilling parties to the infidelity. Each is betrayed, not betrayer. There aren’t any easy fixes for the fictional characters — no hightailing it to a sex rehab clinic or laughing it off with latenight jokes. But there is plenty of drama — and dark comedy — in their predicaments. “A Serious Man,” for example, is set into motion when Larry Gopnik’s wife tells the hapless physics prof she is having an affair. George Clooney’s corporate terminator starts to fall for a fellow traveler in “Up in the Air,” only to discover she has hidden marital baggage. And “Precious” reveals incest’s horrific toll on a family. Yet none of these movies are about infidelity the way, say, “Unfaithful,” was. The Coen brothers imbue “A Serious Man” with a strong sense of time and place; it is as much about Judaism in 1960s Minnesota and the filmmakers’ warped sensibility as it is about cuckoldry. Ryan Bingham’s disappointment about his mile-high partner in “Up in the Air” is part of an overall awakening about the emptiness of his life; the infidelity of Precious’ father to her mother pales in comparison with his incest and her mother’s anger about it. And Jenny’s discovery of her lover’s wife — and his repeated affairs — makes the British schoolgirl appreciate her parent’s staid values and the folly of easy shortcuts in “An Education.” Infidelity, in other words, is a versatile plot device. “It’s interesting, it’s common, and it’s juicy,” says Wesleyan U. film scholar Jeanine Basinger. “You can tell it as comedy, drama, whatever.” And from a screenwriting standpoint, “it’s a doable crime,” Basinger observes. “It’s the thing everybody knows could happen.” When the character — or public figure — had a pristine image like Woods, so much greater the fascination. “Feet of clay interest us greatly,” she says. “We think, oh, he’s a great golfer, but not that good a husband.” Bobby Goldstein, executive producer of the syndicated “Cheaters” reality show, has a simple explanation for the profusion of adultery stories: “It’s the drama of life.” The former lawyer, who will begin the 11th season of “Cheaters” in the fall, says he used to worry about running out of cases in the beginning. “Turns out, we’ll run out of film and money before we run out of adultery,” he says, noting his show gets more than 400,000 investigation requests annually from around the world. Psychologist Gary Solomon won’t argue the prurient interest in infidelity onscreen and off. But he doesn’t consider it healthy. The Movie Doctor, as he calls himself, advocates cinema therapy for patients grappling with drug or alcohol abuse or death and dying in lectures and books. Not so infidelity. “This is a terrible betrayal that we do to each other,” he says, lamenting the lack of consideration shown for children affected by onscreen and offscreen shenanigans. “This is entertainment at another’s expense.” Regardless the moral value, movies about infidelity will surely keep coming. It may be none of our business, but transgressions by the Tiger Woods of the world provide great theater. “And that’s material for film and TV storytellers,” Basinger says.