“That’s out the door compared to 2005,” Felder says, estimating that the number of postnups done at his firm has increased by 10 to 15 percent a year over the last two decades or so. “It’s becoming a major part of a divorce lawyer’s business.”

Lawyers and sociologists point to several reasons for the increased interest in these contracts, which try to wall off a specific portion of wealth from the marital pie. One of the things that got the ball rolling was the divorce of Gary Wendt, who was the chief executive of G.E. Capital at the time.

Lorna Wendt, a stay-at-home mother, sought half of her husband’s assets, contending that she was essentially his business partner, having supported his career over the years. In 1997, she was awarded about $20 million, or nearly half her husband’s hard assets.

The willingness of the Connecticut court to delve into how much Gary had made during the marriage and to designate such a large portion of it as marital property was a watershed moment, given that, prior to the Wendt case, the courts had generally sought to calculate how much a stay-at-home spouse needed for support, not whether that spouse was entitled to a large share of the couple’s total wealth.

“That was a wake-up call to a lot of people who had accumulated a great deal of wealth since marrying,” says Evergreen State College’s Coontz.

Some seeking postnups are just trying to protect assets for children from a previous marriage. But many of those queuing up at their lawyer’s offices are already nine-tenths of the way to divorce and just don’t want to pull the trigger; they see the postnup as a way to take some thorny issues off the table. Others are laying the groundwork for divorce and want to tie up what could be some messy ends before popping the news. Lawyers say that spouses who are running family businesses or who are involved in partnerships may worry about losing control of their assets or about a forensic accountant leafing through their books.

Whether postnups are good news for modern relationships is another question. They can’t deal with important issues such as child custody and child support payments. And not all states give postnups the same weight, with lawyers saying they tend to hold up better in New York courts than in Connecticut or New Jersey courts, for example. Also, the agreements can often heighten the very concerns they are supposed to take off the table.

The postnups that seem to work best tend to be those that address the concerns of women who stay home to raise a family. The spouse who sacrifices a career to stay at home with children or quits her job to move with a spouse, can benefit from a postnup, because the agreement is protecting one spouse who is giving something up for the other.

But Alter says these cases are rare, adding that she’d rather steer clear of doing most prenups or postnups, “because it is so hard not to make the relationship worse.” Asked what she’d prefer, Alter responds, “I’d rather do a divorce.”