It’s a good day when Frank Lee, a retired chef, can slip out to the hardware store, fairly confident that his wife, Robin, is in the hands of reliable help. He spends nearly every hour of every day anxiously overseeing her care at their home on the Isle of Palms, a barrier island near Charleston, S.C.

Ms. Lee, 67, has had dementia for about a decade, but the couple was able to take overseas trips and enjoy their marriage of some 40 years until three years ago, when she grew more agitated, prone to sudden outbursts and could no longer explain what she needed or wanted. He struggled to care for her largely on his own.

“As Mom’s condition got more difficult to navigate, he was just handling it,” said Jesse Lee, the youngest of the couple’s three adult children. “It was getting harder and harder.”

“Something had to change, or they would both perish.”

Frank Lee’s search for trustworthy home health aides — an experience that millions of American families face — has often been exhausting and infuriating, but he has persisted. He didn’t entirely trust the care his wife would get in an assisted-living facility. Last August, when a respite program paid for her brief stay in one so Mr. Lee, 69, could take a trip to the mountains, she fell and fractured her sacrum, the bone that connects the spine to the pelvis.

There is precious little assistance from the government for families who need a home health aide unless they are poor. The people working in these jobs are often woefully underpaid and unprepared to help a frail, elderly person with dementia to bathe and use the bathroom, or to defuse an angry outburst.

Usually, it is family that steps into the breach — grown children who cobble together a fragile chain of visitors to help an ailing father; a middle-aged daughter who returns to her childhood bedroom; a son-in-law working from home who keeps a watchful eye on a confused parent; a wife who can barely manage herself looking after a faltering husband.

Mr. Lee finally found two aides on his own, with no help from an agency. Using the proceeds from the sale of his stake in a group of restaurants, including the popular Charleston bistro Slightly North of Broad, he pays them the going rate of about $30 an hour. Between his wife’s care and medical expenses, he estimates that he’s spending between $80,000 and $100,000 a year.

“Who the hell can afford this?” he asked. “There’s no relief for families unless they have great wealth or see their wealth sucked away.” He worries that he will run out of money and be forced to sell their home of more than three decades. “Funds aren’t unlimited,” he said.

Credited with emphasizing local ingredients and mentoring young chefs in Charleston, Mr. Lee retired in 2016, a few years after his wife’s diagnosis.

In an interview at the time, he said, “My wife has given up her life to help me in my career, and now I need to pay attention to her.”

In 2020, he contacted a half-dozen home care agencies. Some couldn’t fill the position. Others sent aides who were quickly overwhelmed by his wife’s behavior. Doctors told the family they believed she has frontotemporal dementia, which appeared to affect her language and how she behaved.

One woman seemed promising, only to quit after a week or two. “We never saw her again,” Mr. Lee said. He tried a friend of the family for a time, but she left when her grandmother developed liver cancer.

“It was the whole year of going through different caregivers,” his son Jesse said.

Finally, Mr. Lee found two to help. One of them, Ronnie Smalls, has more than a dozen years of experience and is trained in dementia care. She has developed a rapport with Ms. Lee, who seems reassured by a quick touch. “We have a really good bond,” Ms. Smalls said. “I know her language, her expression.”

One day at the Lees’ cozy one-story house, decorated with furniture made by Ms. Lee, and with a yard overflowing with greenery, Ms. Smalls fed Ms. Lee lunch at the kitchen table with her husband and daughter. Ms. Lee seemed to enjoy the company, murmuring in response to the conversation.

At other times, she seemed oblivious to the people around her. She can no longer walk on her own. Two people are often needed to help her to get up from a chair or to go to the bathroom, transitions she often finds upsetting. A day without an aide — out because of illness or a family emergency — frays the tenuous links that hold the couple’s life together.

Mr. Lee says his wife barely resembles the woman he married, the one who loved hiking, skiing and gardening, and who started a neighborhood preschool while raising their three children. A voracious reader, she is now largely silent, staring into space.

The prognosis is bleak, with doctors offering little to hang onto. “What’s the end game look like?” Mr. Lee asks, wondering if it would be better if his wife had the right to die rather than slowly disappear before his eyes. “As she disintegrates, I disintegrate,” he said. She recently qualified for hospice care, which will involve weekly visits from a nurse and certified nursing assistant paid under Medicare.

Charleston is flush with retirees attracted by its low taxes and a warm climate, and it boasts of ways to care for them with large for-profit home health chains and a scattering of small agencies. But many families in Charleston and across the nation can’t find the help they need. And when they do, it’s often spotty and far more expensive than they can afford.

The vast majority of Americans want to remain in their own homes, living independently, for as long as possible. They want to avoid nursing homes, which they see as providing poor care, polls have found. And the ranks of older people who need such help will grow. By 2030, one in five Americans will be at least 65 as millions in the boomer generation retire.