Early-onset Alzheimer's stole the memory of his marriage. Then he proposed again.

Peter and Lisa Marshall's romance began 20 years ago, after the former neighbors had each gotten divorced. They lived in different states and maintained a long-distance relationship for eight years, as neither wanted to uproot her kids. After Lisa's youngest went off to college in 2009, the couple decided to get married.

A dream Turks and Caicos beach wedding followed. Lisa moved to Peter's home in Connecticut, where they enjoyed seven years of marital bliss. Then the warning signs hit.

Peter started giving Lisa directions to their home. He began having trouble finishing sentences, struggling for the words

"Instead of the word 'airplane,' he'd say, 'that thing that goes up in the sky,' " Lisa told The Washington Post. "He also became pretty forgetful, but the word deficiency was really hard to ignore."

Peter went to a neurologist in 2018 and was diagnosed with early-onset Alzheimer's. He was 52.

"Before his diagnosis, I always thought that Alzheimer's was an old person's disease," Lisa told the Post. "Now I know better."

Peter's cognitive impairment accelerated quickly. By January of 2019, he had to quit his job. The following year, Lisa quit hers to become his full-time caretaker.

Needless to say, it's been an incredibly difficult journey for Lisa, and well as the couple's five children, as Peter's memory of his life and loved ones fades—including his memory of being married to Lisa.

But late last year, a beautiful moment of hope broke through the darkness. Lisa and Peter were watching a show that featured a wedding when Peter suddenly looked over at Lisa and said, "Let's do it!"

"Do what?" Lisa asked.

Peter pointed to the wedding scene on the TV.

"Do you want to get married?" Lisa asked.

With a big smile, Peter said yes.

"Well, okay," Lisa responded. "We should get married then."

He wouldn't remember the proposal the next day, but the idea of renewing their wedding vows resonated with Lisa. "For better or for worse" had taken on a whole new meaning after Peter's diagnosis, and his condition has worsened since January of this year. For the past six months, he has seen Lisa as his favorite caretaker, not his wife.

Lisa's daughter, Sarah Brehant, runs a wedding planning business and offered to organize the ceremony. She networked with vendors, who all offered to provide their services for free.

"I knew that my stepdad, who I am very close with, was there through some of the toughest times of my life," Brehant told the Post. "He means so much to me, and my mom is my best friend, so I was proud to be able to take on such an important role."

Sarah wrote in a touching Father's Day post that Peter had started telling her he loved her every chance he got after his diagnosis.

"I knew he wanted to make sure I knew before he couldn't tell me anymore," she wrote. "He'd say it every chance he could get while he still could, every time we saw each other."

Peter and Lisa renewed their wedding vows on April 26 in a ceremony attended by friends and family and officiated by a dementia specialist who helped Lisa set up a care plan for Peter.

"It was just magical — straight out of a fairy tale," Lisa said.

When Lisa got to the altar, Peter leaned in and gave her a kiss.

"There wasn't a dry eye, and I was over the moon," she said. "I hadn't seen Peter that happy in a long time."

"It was absolutely magical," Sarah told The Knot, "and Peter was bright and present the entire day. The sweetest moment of the day was when he had a very lucid moment and he leaned in and whispered in my ear, 'Thank you for staying.'"

Watch this beautiful video of highlights from the big day:

Emotional Vow Renewal // Mill 1 at Open Square // Lisa + Peter www.youtube.com

As lovely as the vow renewal was, it would be disingenuous to leave the story there. Lisa has been documenting the couple's Alzheimer's journey—the inspiring and the challenging—via her Facebook page Oh Hello Alzheimer's. In her posts, it's clear what an up and down experience it is to love someone who is losing themselves.

On June 14, Lisa shared a bittersweet post about the difficulty of watching Peter disappear, only to be reassured by him when she cried into his chest, "We still have time."

Then, just five days later, Lisa shared a post about how Peter's condition has reached a point where the daycare that gave Lisa a respite from full-time care was no longer viable as he's grown more anxious and agitated. Alzheimer's patients can become increasingly paranoid and hallucinate as the disease progresses, which can lead to anger and aggressive behavior.

"I knew the call would come," Lisa wrote, "I was well aware that it would happen. I just thought I'd have more time."

The decisions about care for a loved one with advancing Alzheimer's are never easy, and time is never guaranteed. Although Lisa and Peter's story is hard to witness, her openness is also providing solidarity and support for countless families who are going through similar experiences with their loved ones.

Lisa has also used her Facebook page to raise money for Alzheimer's research, and after seeing Peter's story, it's obvious why it's so needed. As Lisa reminds us, Alzheimer's is a terminal disease, and as of now, there is no cure. You can donate to the Alzheimer's Association via Lisa's team link here.

As for advice for other couples, "The only thing that matters is love and respect," Lisa told The Knot. "You treat each other with gentle kindness every day and you reach deep into your heart for more patience and understanding than you think you have. You love deeply and immensely and you make memories intentionally. Be present."

Despite Peter forgetting her, Lisa added, "I'm the luckiest woman in the world. The man of my dreams fell in love with me and asked me to marry him twice. He chose me again."

All our best to Lisa and Peter as they navigate their remaining time together.