Sixth in a series.

Rhonda was a big woman, and Floyd liked that. She was 5 feet 9 inches tall, with bold red hair and a plus-sized personality. If there’s a photo out there somewhere in which she’s not smiling, it has never been found.

Floyd Rasmussen met Rhonda Sue Ridge at a church dance on New Year’s Eve 1973, when she was just 17. He was 31, a Vietnam vet with three kids and an ex-wife. His first marriage was a casualty of war, and he’d spent a few years carousing in Southern California before finding religion. He’d become a Mormon. As he slid across the room, angling for the pretty redhead, he didn’t realize she hadn’t yet graduated from high school. He asked her to dance.

Rhonda thought: Why is it always the old guys?

They married the next year, soon after her 18th birthday. Under church doctrine, they became “sealed,” meaning their bond was not only unbreachable in this life but for all of eternity.

Their connection was more than doctrinal. Floyd and Rhonda had a visceral attraction that would survive all the stresses of age, money worries, child-rearing and no fewer than 27 relocations as they jumped from one military job to another. They raised four kids (Floyd didn’t see much of his three older children). As Mormons, they believed that the man ruled the family, but in practice it was Rhonda who served as CEO of what she called Rasmussen Inc. When they posed for a family photo, she sat front and center, with Floyd behind her and the kids orbiting like planets around a star.

Family took priority for Rhonda, but in 1991, when they were stationed in Germany, she took a leap into the unknown. She enrolled in an MBA program at Syracuse University, traveling to Upstate New York with the two youngest kids and leaving Floyd and the two older boys in Germany. There was much anguish in the Rasmussen household. Floyd told Rhonda that he supported her decision, but that he was uneasy. Floyd needed Rhonda — maybe a bit more than Rhonda needed Floyd. He was trundling into middle age, while she was still in her 30s. He had to wonder: Would she ever come back?

Letters flew to and fro across the Atlantic. Floyd was always better than Rhonda at putting his love into words.

This is what he wrote — it so happens — on Sept. 11, 1991:

“I awoke this morning with an overwhelming sense of your presence near me, it was so strong that I felt that I could reach out and take you in my arms.”

A few days later, he wrote:

“Your absence rents my heart and soul, I am torn asunder. There is a void in the very center of my being, which nothing, other than you and your love, can begin to satisfy.”

She did come back, of course, and kept coming back after other assignments pulled them temporarily apart. When Floyd was in his late 50s, congestive heart disease was diagnosed. When he turned 58, Rhonda gave him a birthday card that said, “Babe, with all your sickness and your faults I still love you! . . . Hopefully we will be able to enjoy these next 58 years to their fullest. Love, Red.”

In March 2001, they relocated again, to Northern Virginia to take Pentagon jobs. On Sept. 10, they learned that they’d been accepted for government jobs at the Presidio in Monterey, Calif. Let’s skip work tomorrow, they decided. They could spend Sept. 11 preparing for the next phase of their lives.

Morning came and they changed their minds. Rhonda needed to attend a meeting. Duty called. And so at dawn, they drove north on the interstate from Woodbridge, arriving at the Pentagon at 6:30 a.m.

The Rasmussens had a combined 39 years with the military, but they were civilians, not warriors. Floyd dealt with personnel issues, office passes and parking space assignments. Rhonda was an Army budget analyst. They said good-bye in a hallway, and Floyd headed to his office on the third floor while Rhonda went to her cubicle on the first.

Around 9 o’clock that morning, Floyd received a phone call from Rhonda with startling news: A plane had hit one of the towers of the World Trade Center. He assumed it was an accident. Throughout the Pentagon, workers began crowding into managers’ offices to watch television, but Floyd focused on his immediate tasks, including finding out why some telephone lines had gone down in another part of the building.

At 9:37 a.m., he felt a jolt and momentarily lost his balance.

His boss came out of his office screaming, “Evacuate!”

Floyd knew what to do: He ran through a hallway, down two flights of stairs and out a door into the bright sunlight of the Pentagon’s interior courtyard. Soon he joined colleagues as the building was emptied. He found himself amid chaos as fire trucks converged, sirens blared and smoke filled the sky. He began looking for Rhonda amid the crowds. “I’m here, come find me!” he shouted.

Rhonda did not appear.

Floyd waited for one, two, three hours. He got no answer on her cellphone. Maybe she’d headed home, somehow.

He couldn’t get to his car, so he rode home with a stranger. Their teenage daughter, Bekki, hugged him as he walked through the door. “Have you seen Mom?” Floyd asked. She hadn’t.

It was right around 7 p.m., as he watched the TV news and got his first good look at the gash in the side of the Pentagon, that the dread he’d been fighting off all day hardened into an awful revelation. The plane had made a direct hit on Rhonda’s office. And he thought: They’re not going to find a trace of her.

The Army medical examiners worked 12-hour shifts in the military mortuary in Dover, Del., trying to identify the remains. They called in forensic anthropologists and forensic dentists. A severely charred tooth can sometimes retain its shape well enough to permit an identification through dental records.

Floyd brought Rhonda’s toothbrush to Army authorities and his daughter donated a blood sample. These contributed to a DNA database of everyone believed to be a victim. Samples of recovered tissue were placed in plastic tubes and transported to the Army pathology lab in Rockville for analysis.

Floyd waited for news, going day after day to a hotel where family members of the missing gathered. Pinned to his chest was a picture of Rhonda from her recent 25th high school reunion.

The Boeing 757 had hit the first floor of the Pentagon and disintegrated into thousands of metallic projectiles immersed in more than 5,000 gallons of exploding jet fuel. It was like an enormous flaming shotgun blast. It tore through the building at an angle and punched a hole in the wall.

They found remains of the woman who sat on one side of Rhonda and of the man who sat on the other. They were able to identify the remains of 179 of the 184 victims and of the five hijackers.

Five people, though, vanished in the conflagration. Floyd was right that night when the truth dawned on him. No one would ever find an identifiable trace of Rhonda Sue Ridge Rasmussen.

Floyd went ahead and moved to Monterey. But he was at the bottom of a sea of sadness. After just 10 months, he retired from government work.

Floyd relied on faith to sustain him. His agonized revelation on the night of Sept. 11 had been coupled with an intense spiritual awakening. He felt certain that the doctrine was correct, that he would be reunited with Rhonda someday, and that she would be restored to perfection.

Meanwhile, he had problems. His health was poor. He needed someone. What he really needed, and what he wanted, was Rhonda. And so he decided to look for her to the extent that such a thing might be possible. He went online, to Yahoo Singles.

“I was looking for a woman who was 5-6, red hair and a Mormon,” Floyd says. “And Brenda turned up.”

Brenda Barnum: divorcee, 37 years old, mother of a grown daughter, Mormon, pretty, redheaded.

Brenda wasn’t nearly as big or as tall as Rhonda, but she wasn’t a wisp, either. She described herself in her online profile as “Rubenesque,” and a lover of the outdoors. She’d gotten tired of the singles scene — “a snake pit” — and of all the “old, fat, bald men looking for Barbie.”

Floyd and Brenda met in San Jose, just down the highway from Stanford, where Brenda worked. She had no idea what he would look like, or his age. And she didn’t know the back story. She didn’t know that this man driving up in the sports car, looking snazzy, with an astonishing white beard and a shaved head, was a widower whose wife had been killed by the 9/11 terrorists.

He was, Brenda realized, at least 20 years older than her. She thought: Why is it always the old guys?

They had dinner and saw a movie, and at the end of the night she lifted up his white mustache to see what was hiding under there.

“I saw these perfect lips, and I thought, ‘Okay, I could go out with him.’ ”

The Rasmussens now live in Vancouver, Wash., just across the Columbia River from Portland, Ore. The walls are covered with family photos of Floyd and his pretty, crimson-haired bride. Brenda, not Rhonda. In the stairwell, there’s a portrait of Floyd, Rhonda and their four kids.

Floyd: “The first time I met Brenda, I knew she was exactly the kind of woman I was looking for. We had the same religious beliefs. She looks much like Rhonda. And even Rhonda’s brothers — ”

Brenda interrupts: “They thought I was her. . . . It’s the hair and white skin.”

Before they married, Floyd brought Brenda to meet Rhonda’s mother, Alene, and asked if she would approve of the marriage.

“She approved, and she was sure Rhonda would have, too,” Floyd says.

Floyd and Brenda were wed in a chapel in Seaside, Calif., and several years later became sealed in a ceremony at the Mormon temple in Portland, Ore. But Floyd remained sealed for eternity to Rhonda as well. Floyd explains:

“A man can be sealed to more than one woman, but a woman can only be sealed to one man. It’s back to the 1880s, when polygamy was there. I can be polygamous but a woman can’t be polyandrous.”

If there’s one thing that Floyd Rasmussen isn’t these days, it’s alone. His modest Vancouver home has a permanent canine soundtrack as four dogs of different sizes and breeds hustle about. On a sunny afternoon, a neighbor drops off fresh berries that Brenda will turn into jam. Floyd’s adult son Jeremiah, still finding his way in life, will be home from work soon. And Floyd’s mother, Alice, is here, quietly reading “The Greatest Generation” and occasionally commenting on how much the world has changed.

The big question mark is how much longer Floyd will live. He needs a new kidney, and Brenda wants to donate one. He’s coming up on 70, and doubts he’ll see 75.

It’s a Wednesday morning in Portland, and Floyd is sleeping in his hospital bed in the dialysis ward at the Veterans Affairs hospital overlooking the city. Brenda huddles under a blanket in an adjacent chair. A nurse fiddles with a humming refrigerator-sized contraption that filters Floyd’s blood. This is their life, three days a week.

Floyd stirs, and wakes up just enough to fumble with a plastic-wrapped egg-salad sandwich. He doesn’t quite get any of it in his mouth before he drifts off to sleep again.

Here in the hospital, with Floyd unconscious, Brenda turns candid about life in the shadow of Rhonda.

“We have a really good marriage now. But the beginning part was miserable. To get to where we are now, we had to go through that. He wanted me to be like her, he wanted me to step in and know all the stuff she knew and do all the stuff she did and practically be her.”

The man who looked like such fun turned out to be emotionally devastated and physically deteriorating. Two weeks after they married, Floyd’s renal failure was diagnosed. He took to his bed. Brenda realized that he remained deeply depressed by Rhonda’s death, that he wasn’t healing. And then she felt her existence evaporating into the black hole created by the terrorists.

“Literally he spent a year in bed, crying and grieving. And at first he wanted me there to hold. And I just couldn’t stay in bed all the time.”

Floyd’s needs threatened to swamp even the prodigious nature of Brenda’s love. They went to counseling and talked through the obvious fact that Floyd wanted Brenda to be Rhonda. The therapy helped.

Floyd began to appreciate Brenda more — for being Brenda.

At home in Vancouver, Brenda boots up her computer and sticks in a disk loaded with photographs of Rhonda. Floyd can’t see well, so it’s Brenda who narrates. This is my favorite picture of her, Brenda will say.

Brenda has become Rhonda’s curator. She doesn’t try to channel Rhonda, but she knows things that Rhonda would have known. With Brenda’s help, Rhonda is still very much a presence.

“There’s plenty of room for both of us. And I’ve gotten to know her. The term is ‘sister wife.’ And she’s a part of who we are. And I’m a part of her marriage. There’s no jealousy. She got the young half and I got the old half. I’m perfectly happy with that.”

Floyd never tries to gloss over events. He doesn’t like it when people talk about 9/11 victims as “heroes” — what’s heroic, he says, about going to work and sitting at a desk? The world according to Floyd isn’t some fairy tale in which everyone magically lives happily ever after.

But it’s one in which people do their best to fill the voids.

He says, “We’re living hopefully ever after.”

First in the series: Trying to find the new normal

Second in the series: Twin misses his other half

Third in the series: Brought together by catastrophe

Fourth in the series: After 9/11, security guard on high alert

Fifth in the series: Still feeling at home up in the sky

Seventh in the series: The wounded man

Eighth in the series: Living with ‘if only’

Ninth in the series: The skeptic who was there