It is incredibly difficult to be responsible for the full-time care of another adult. That is how many people make their living, which is, unfortunately, not as well-paid as it should be; however, many people do this work for their family members for free. It’s not like there’s a season where somebody who requires full-time care doesn’t need that care. It’s a 24-hour-a-day, 7-day-a-week gig. A dependent sick person isn’t a project that can be put on the back burner while someone takes a break from caring for them.
It can be frustrating when a loved one is sick in a way that they can actually do the work to manage, but they refuse to manage it. There’s a big difference between being helpless to improve your condition, or doing everything the doctor says to no avail, and actively ignoring advice or coping strategies that could actually help one recover.