Can you fall back in love?

But he also knows if it didn’t work the first time after five years of marriage, there is no reason to believe a second time would be successful. “The feeling isn’t there,’’ the case information specialist at Astra Tech in Waltham, said. “It’s emotion. It’s either there or it’s not.’’

But is it really that simple? Or can you fall back in love? That delicate dilemma was raised by South Carolina Governor Mark Sanford in June, when he tearfully admitted he had “crossed lines’’ with a handful of women, that he’d had an affair with an Argentinean woman, Maria Belen Chapur, and that he was now going to try to fall back in love with his wife of 20 years, Jenny. Skeptics scoffed that the presidential hopeful was merely trying to salvage his political future, but regardless of his intentions, he raised a question that relationship counselors say comes up more often than you might think.

There is no consensus, but Anthony Centore, director of Thrive Boston Counseling and Psychotherapy, and other specialists do say that it’s possible to fall back in love with someone - with work. “A lot of people come in and they think they can never feel the way they did,’’ Centore said, “but after they start going through the [therapeutic] process, their skepticism starts going away.’’

The National Center for Health Statistics stopped collecting detailed data on divorce in 1996. But Andrew J. Cherlin, a professor of sociology at Johns Hopkins University, and author of “The Marriage-Go-Round,’’ predicts that 40-to-50 percent of marriages will end in divorce, with second marriages slightly more likely to end than first marriages.

There are no numbers on the success of second marriages to the same person, although if Hollywood is any gauge, it isn’t breaking up that’s hard to do. It’s getting back together. The celebrity list of serial on-again-off-again lovers includes Richard Burton and Elizabeth Taylor, Sean Penn and Robin Wright Penn, Melanie Griffith and Don Johnson, Eminem and Kim Mathers, and Tommy Lee and Pamela Anderson.

Kevin Murphy, 51, a metals recycler from Quincy, was close to going down that on-again-off-again road with his girlfriend. He said they were happy - until they moved in together - when they started arguing about everything from what time to go to sleep at night to the mess and clutter he brought into their shared place (an excess of books and magazines, and grimy antique furniture). “We did think about breaking up,’’ he acknowledged.

But counseling brought the pair closer, and reminded him what he loves about his girlfriend. She’s outgoing and introspective, goal-oriented, and, he added, “a real sweetheart.’’ The key, he said, was “remembering that you once thought the world of this person, and she thought the world of you.’’ Now, he gushed, they are engaged.

Helen Fisher, a biological anthropologist at Rutgers, says falling back in love makes sense scientifically. “The brain system can be retriggered, just like the fear system,’’ said Fisher, chief scientific adviser to Chemistry.com, a division of the dating site Match.com. “You can be afraid of something, get over it, and then become afraid again.’’

But not everyone believes the same is true of love. Jim Duzak, the author of “Mid-Life Divorce and the Rebirth of Commitment,’’ and a former divorce attorney, said his thoughts are best summed up by Lord Wavell, a British commander in World War II, who compared love to a cigar. “If it goes out you can light it again,’’ Wavell said, “but it never tastes quite the same.’’

“Sometimes people wrongly convince themselves they’re in love again because they’re afraid of the future,’’ Duzak said. “But usually there were good reasons why the people broke up. And yeah, with the passage of time you can perhaps persuade yourself if you give it another try it will be different. But if you broke up because he’s a self-absorbed narcissist, the chances are that he’s still a self-absorbed narcissist.’’

That’s consistent with research conducted by Thomas Bradbury, a psychology professor at UCLA and codirector of the UCLA Relationship Institute. His research shows that “falling back in love is possible, but exceedingly rare, especially after major rifts have developed,’’ he said by e-mail.

People in counseling often speak of “working’’ on relationships. But to many, that seems like a strange approach to handling love. “It’s not something you have to try to do,’’ said Guerin, the divorced dad from Dorchester.

Perhaps, but therapists say that waiting to be thunderstruck may also be the wrong approach. “The whole concept of ‘falling’ in love is too passive and never applies to a mature, loving relationship,’’ said Mark Sharp, a psychologist with a family practice in Oak Brook, Ill. “People often treat love as this kind of thing that exists outside of them, and they just step into it and then it works. Love requires some action and intention from the people who are in love.’’

Of course, sometimes intentions aren’t enough to repair a damaged relationship. The Sanfords would seem to be a case in point. Earlier this month, Jenny Sanford and the couple’s four boys moved out of the governor’s mansion, and just this week she told Vogue magazine that her husband’s affair was almost like an “addiction.’’ “I have put my heart and soul into being a good mother and wife. Now I think it’s up to my husband to do the soul searching to see if he wants to stay married. The ball is in his court.’’

As the Sanfords’ relationship plays out in the media, a Wayland couple about to celebrate their 20th anniversary offered advice on how to keep a marriage going.

“Sometimes you don’t feel like you’re in love, but you have to follow through on your commitment,’’ Jeffrey Cohen, 55, a real estate developer, said as he headed to meet his wife and daughters at Charley’s on Newbury Street. “Ask my wife,’’ he said cheerfully. “She’ll tell you.’’

Found sitting at an outdoor table at Charley’s, Dana Jackson Cohen, 48, shared her opinion. “There are some days I look at him and I love him so much,’’ she said, “and some days I’m like - ’’ she shrugged. Asked to translate the gesture, she said: “Who am I with?’’

Her husband looked on happily. “See,’’ he said, grinning. “I told you she’d have something to say.’’

But rather than look to ordinary marriages for answers, perhaps Sanford should turn to poetry - or Broadway.

Is love the romantic ideal that John Keats wrote about? “Two souls with but a single thought, two hearts that beat as one’’?

Or is it the practical matter described by Golde in “Fiddler on the Roof,’’ when Tevye asks if she loves him? “Do I love him?’’ she sings, “For twenty-five years I’ve lived with him/Fought him, starved with him/Twenty-five years my bed is his/If that’s not love, what is?’’