Beware of long marital engagements.

Their primary peril:

A protracted wait from proposal acceptance to wedding date boosts the risk that somebody who agreed to say “I do” will later say “I won’t.”

You can then lose not just face but deposits — and friends who booked vacation times, flights and lodgings in costly vain.

But those aren’t the only hazards of extended engagements.

For instance, if you’re a member of Congress, taking your sweetie on an overseas junket is easier if the two of you are already married.

And if you’re also an ex-governor who remains a national punch line for running out on your then-wife — and your elective-office duties — by leaving the country in 2009 to see the woman who’s now your fiancee, why rekindle the ridicule fire?

Of course, if you are part of a group of U.S. House members getting a free ride to Israel, and the rest of that bunch was invited to bring a family member (most lawmakers choose spouses) at no charge, you might want to bring your significant other, too.

So that’s just what 1st District Rep. Mark Sanford did on an Aug. 10-18 excursion paid for by the American Israel Education Foundation.

As my esteemed colleague Schuyler Kropf reported in Wednesday’s Post and Courier, though such trips are “usually limited for relatives,” the House Ethics Committee granted a waiver so Sanford could bring along Maria Belen Chapur, to whom he’s been engaged for more than a year.

So happy together

Our story added: “The AIEF spent more than $18,558 to fly Sanford and his fiancee to and from Israel for the weeklong journey, the National Journal said. The pair flew business class, records show, with round-trip flights that cost more than $5,000 apiece.”

And: “In a statement issued by Sanford’s Washington office, his spokesman noted that the trip was privately funded and was bound for an important region of the world. Also, that nearly two-thirds of the freshman Republican class were participating.”

Yes, despite limiting himself to three House terms (1995-2001), Sanford is officially a congressional rookie again after winning May’s special election.

And he’s still drawing unfortunate, unnecessary attention to his love life — in this case because he’s still unmarried.

Let that be a lesson for reluctant grooms — and reluctant brides.

Let’s not forget, either, that though Sanford repeatedly makes himself look the fool for love, he makes good sense on many crucial issues.

For instance, he wisely opposes attacking Syria, telling us during a recent visit to this newspaper:

“I don’t think anybody is anything less than appalled by what’s going on in Syria right now. But the question is, ‘What can we do about it?’ ”

Hey, now we can do this:

Trust Russia’s Vladimir Putin and Syria’s Bashar al-Assad on a chemical-weapons-control deal.

Huh?

But enough about our president’s serial Syria blunders and our congressman’s policy insights and personal eccentricities.

Sanford’s not the only one who shouldn’t put off getting married. Far beyond the pitfalls of singledom and long engagements for politicians and other celebrities lies this troubling sign of our times:

According to the federal government, more than 40 percent of babies born in the U.S. in 2011 had single moms.

In 1965, that figure was 7 percent.

You need not be a sanctimonious busybody to lament that trend’s practical — and collective — consequences.

Sure, some single folks are fine parents. So are some unmarried couples.

And some married couples are lousy parents.

Still, a kid who has a mom and a dad (or a mom and a mom, or a dad and a dad) is generally better off than a kid who doesn’t — and not just economically.

Hometown advantage

Even if you dismiss that conclusion as a reactionary relic, you must admit that our local bottom line would benefit if more folks got married.

Charleston is widely ranked at or near the top of U.S. wedding destinations. We also have plenty of divorce lawyers.

Thus, the more matrimonial ceremonies the merrier for us.

Among our many popular tie-the-knot spots: Magnolia Gardens, the William Aiken House, Lowndes Grove Plantation and Alhambra Hall.

Then again, from my personal experience, the Pickens County Courthouse is an enchanting wedding venue.

And those who are fairly wary of long engagements don’t have to book it months in advance.

Frank Wooten is assistant editor of The Post and Courier. His email is wooten@postandcourier.com.