Entertainment

LIGHTS. CAMERA. ACTION.

Anne Heche said it best: “Love isn’t safe. You can’t trust it will stay the same — you might not feel ready to move on, but you have to.”

Actually, those are the words of relationship expert Marin Frist, Heche’s character on “Men in Trees.” But it describes how Heche and hunky co-star James Tupper just shed their respective spouses and children to be together – a move that echoes the show’s storyline.

A recent “MIT” episode said of its Alaskan setting: “What happens in Elmo stays in Elmo.” But the stories of another supposed on-set romance are now reverberating throughout an industry where co-stars hook up and break up more often than their shows get renewed.

“Let’s face it, some people in the TV industry take Method Acting a little too far,” said Linda Mysel, a TV production manager. “But a lot of these off-screen romances end when the actors leave the show, because the sparks that were being written for them are no longer there to sustain the relationship.”

Who needs singles bars when you’ve got the pickup wonderland of a TV production? “It’s certainly an occupational hazard,” said one writer for a long-running series. “Once actors become involved in real life, they seem to lose their chemistry on camera.”

Heche met the husband she just dumped while making a documentary about her then-lover, Ellen DeGeneres, but she vowed to change her ways for the sake of her son, now 4.

“When I decided to have a [baby], I decided to give them a stable life if I could — I would make that a goal,” she told a Tacoma, Washington, newspaper. “I thought the best way I could provide that stability for my son was to be on a TV show.”

So much for stability. Dr. David Giles, a psychology professor at Lancaster University in England and author of “Illusions of Immortality: A Psychology of Fame and Celebrity,” calls it the “world tour syndrome, where you’re only ever ‘in town’ for five minutes. Celebs struggle with it, hence the rapid turnover of partners/wives in showbiz.”

Perhaps, then, celeb relationships should be judged in dog-years, so that the four-month marriage of Chad Michael Murray to “One Tree Hill” co-star Sophia Bush is comparable to a silver wedding anniversary. Murray and Bush are no longer a couple – although they continue to play one on TV – and Murray is now engaged to an extra on the show, Kenzie Dalton.

On-set breakups can cause chemistry imbalance, as with Adam Brody and Rachel Bilson on “The O.C.” “It totally shows,” posts TV Squad blogger Kelly Woo. “[They’re] not sharing scenes much, and when they do, they’re at odds.”

The airwaves are littered with faded love signals: Roseanne Barr and Tom Arnold (“Roseanne”), Alexis Bledel and Milo Ventimiglia (“The Gilmore Girls”), Katie Holmes and Joshua Jackson (“Dawson’s Creek”), Laura Leighton and Grant Show (“Melrose Place” – Leighton later married co-star Doug Savant), Jennifer Garner and Scott Foley (“Felicity”), Jennifer Garner and Michael Vartan (“Alias”).

But there’s hope: Michael J. Fox and Tracy Pollan met on “Family Ties” and remain married with children 17 years later.

Will that be the fate of Evangeline Lilly and Dominic Monaghan (“Lost”)? Or Kristy Swanson and pro skater Lloyd Eisler (“Skating with Celebrities”)? Eisler left wife and kids for Swanson, and the reformulated couple is expecting a baby on – when else? – Valentine’s Day.

Tori Spelling and Dean McDermott (Lifetime TV movie “Mind Over Murder”) are expecting a baby while developing the series “Tori & Dean: Inn Love” for Oxygen. Kelly Ripa and Mark Consuelos (“All My Children”) are likewise developing a series about their undying love. No one recalls the lessons of “Newlyweds: Nick & Jessica,” or even “I Love Lucy.”

Just last month, James Tupper told an interviewer that his wife was insecure about his love scenes with Heche: “I think any wife of an actor has to put up with a lot.” Or, as Marin Frist would say, “Love isn’t safe.”

MEN IN TREES

Thursday, 10 p.m., ABC