By the time my great-grandparents hit retirement age, my great-grandmother was living with one daughter. My great-grandfather with another. The two rarely saw each other, or spoke. They had, my mother explained, an “Irish Divorce:” two people living separate lives and in all ways strangers, disconnected from each other, sharing only an unhappy past and a pair of wedding rings.

In their era, as Irish Catholics, divorce was not only a social stigma, but a moral sin. And, like most women at the time, a legal divorce would have left my great-grandmother, who had spent her life raising children and caring for a home, penniless.

Today, not only is Pope Francis meeting this month with bishops from around the world at the Vatican to reassess and potentially soften the Catholic church’s position on divorce and annulment, but new research being released on Wednesday shows that Irish Divorce has become a thing of the past.

Since 1990, the divorce rate for Americans over the age of 50 has doubled, and more than doubled for those over the age of 65. At a time when divorce rates for other age groups has stabilized or dropped, fully one out of every four people experiencing divorce in the United States is 50 or older, and nearly one in 10 is 65 or older, according to a new report by Susan L. Brown and I-Fen Lin, sociologists at Bowling Green State University.

But what researchers said they found particularly puzzling – it wasn’t just remarried older people who were getting divorced – remarriages typically don’t last as long as first marriages. And it wasn’t just older people without a college education getting divorced – in younger generations, those with college educations are about half as likely to divorce as those with less education.

More than half of all gray divorces are to couples in first marriages. Indeed, 55 percent of gray divorces are between couples who’d been married for more than 20 years.

“We found that flabbergasting,” Brown said.

Many of the marriages that had dissolved were not marked by severe discord, she said. Rather, the couples had simply grown apart. Much like Al and Tipper Gore, who shocked the world – and their friends – when they announced they were separating in 2010 after four kids and 40 years of marriage.

In fact, Brown said the Gores’ marital dissolution – the couple have yet to actually divorce – was what sparked the research into gray divorce in the first place. What the researchers have yet to figure out is why so many more older Americans are divorcing. And divorce no matter the age group, the researchers note, tends to be initiated by women.

“It’s not as if marital quality has suddenly declined. Instead, I think we have higher expectations now for what constitutes a successful marriage. We expect spouses to be best friends and marriage a source of happiness and fulfillment,” Brown said.

“As women achieve more financial independence and autonomy, frankly, they can afford to get divorced,” she continued. “And after you’ve launched your children and retire, people may realize, ‘Boy, we don’t have much in common, and I could live another 20 years.’ That’s a long time to live with someone you may not be that into anymore.”

In other words, fewer older people are willing to put up with an Irish Divorce anymore. And now, women, in particular, don’t have to. Brown has also written about rising cohabitation rates among older Americans, and a boom in older American online dating sites for singles.

For those in good health and with financial resources, a gray divorce may mean an era of freedom and independence, Brown said. But for others, divorce at an older age increases the risk of falling into poverty.

On average, the researchers note, older divorced Americans have only 20 percent as much wealth as older married couples. And the net wealth of those who’ve been widowed over age 50 is more than twice the wealth for what the researchers call the “gray divorced.”

That raises some important questions.

“Now that they no longer have a spouse, divorced older people have less social support. Relationships with their older children could be compromised as a result of the divorce,” Brown said. “As they age and experience health declines, who’s going to take care of them? Especially if they’re not able to afford the level of care that others with more economic resources have?”

Gray divorce is not solely an American phenomenon.

Elena Stancanelli, a senior researcher at the Paris School of Economics, was equally shocked when she analyzed divorce data in France and discovered that French couples who’d been married for 35 or 40 years are now as likely to divorce as couples who’ve been married for five years.

“There are a lot of questions about why this is happening that I can’t answer. Children grow up and leave home. Couples have to re-negotiate household chores. They finally are able to spend more time on leisure, and maybe that leads to conflict,” Stancanelli said. “But whatever the reasons, I have come to the conclusion that the retirement years have become increasingly critical for marriage stability.”

Researchers like Brown wonder if the rising divorce rate among this older Baby Boom generation will hold true for younger generations, Gen X and Millennials. “As marriage becomes more selective, and more tied to education than in the past, that could help stabilize marriages,” Brown said. In other words, fewer are getting into the kind of arranged marriage that my great grandparents had.

And perhaps, said Stephanie Coontz, a historian who teaches family studies at Evergreen State College, these younger, more selective couples won’t pour all their time and energy into work and their kids, as Baby Boomers did, but save some time for each other. So when the time inevitably comes when work is over and the kids are gone, they won’t find themselves staring across a silent dinner table at a stranger.