As a graduate student at the University of Wisconsin during the final years of the Vietnam War, Pauline Boss learned that not all grief journeys look the same.

While losing a loved one is universally searing and life-altering, Boss found that those with a family member identified as “Missing in Action” faced a unique kind of hell.

With no official proof that their soldier was alive or dead, and no opportunity for a funeral or other ritual of support, their pain, Boss said, “went on and on and on.”

Boss gave a name to this unsettling and uncharted territory: ambiguous loss.

For more than 40 years, she has broadened her research on ambiguous loss to natural disasters such as earthquakes and floods, to 9/11, to airline crashes, to Alzheimer’s and other illnesses that take away a loved one’s mind or memory.

And to abductions.

I called Boss because I was thinking, again, of the family of Jacob Wetterling, forced to navigate ambiguous loss for more than 26 years.

“I don’t want to say that one kind of loss is harder than another, but ambiguous loss is the most stressful kind of loss,” said Boss, professor emeritus in the Department of Family Social Science at the University of Minnesota, who asked to speak in generalities only.

“The families and friends of the missing are stuck in a painful limbo where relationships are brutally ruptured and, yet, grief is frozen.”

In light of potential developments in Jacob’s abduction, is his family’s painful limbo about to end?

I’m certain I’m not alone in hoping so, and not hoping so, unless it’s of the miracle variety.

“People understandably maintain hope,” Boss said, reflecting on decades of research. “And sometimes, just enough times to keep hope alive, a missing person does come walking out of the jungle or a kidnapped child is found alive.”

Eleven-year-old Jacob was abducted from rural St. Joseph on Oct. 22, 1989, as he headed home from a convenience store with his brother, Trevor, 10, and best friend, Aaron Larson, 11.

On Oct. 28 of this year, Daniel James Heinrich, 52, was arrested at his home in Annandale on charges of receiving and possessing child pornography. At a news conference the next day, authorities said they are investigating Heinrich’s possible link to the Wetterling case.

The announcement buoyed longtime residents of St. Joseph, for whom the terrifying abduction redefined the way they were raised. Jacob was, and remains, a beloved native son. The local clinic in this college town 75 miles northwest of the Twin Cities still displays a poster with a yellow ribbon and candle proclaiming “Jacob’s Hope.” Porch lights still glow for a night in October.

As news unfolds, the kindest gift we can offer the Wetterlings and others facing ambiguous loss is unlimited patience, Boss said.

“Don’t say, ‘It’s time to move on.’ People hate that line,” Boss said. “People do move forward with their life. They raise other children and go to work. But to move on implies that you want them to get over it. That’s a real insult.”

After Malaysia Airlines Flight 370 mysteriously disappeared with 239 people aboard in 2014, Boss reached out to assist therapists in China, where most of those on board were from.

“The therapists were very wise,” Boss said. “They knew they shouldn’t say get over it.” The officials, on the other hand, didn’t.

In July, more than 16 months after the plane’s mysterious disappearance, plane debris was found on an Indian Ocean island. And, yet, with no bodies yet recovered, many families still hold out hope.

Boss understands this. She advises families to adopt what she calls “both-and” thinking.

“They might be dead, but maybe not,” she said. “People can actually have a good life because they are willing to live with ambiguity.”

Our job is to learn to live with it, too — “to stretch our own tolerance for unanswered questions.”

Boss, who is writing a book about the “myth of closure,” said that, even after a body is recovered, the family forever carries their experience of loss. “Research now tells us that people don’t get over loss, nor do they have to,” Boss said.

“Instead, they live with grief which oscillates in ups and downs over time, not as obsession, but as normal remembering. Years after, there may still be a tear now and then. This is normal human behavior.”