Watch someone fight to lift a fork with locked-in syndrome, or beg for air with late-stage ALS. That's when you get it. My grandpa's cancer turned him into a skeleton who screamed if the sheets touched his skin. We called keeping him alive "care," but it was just torture with a heartbeat. The line isn't about being sad, it's about being forced to live a nightmare with no waking up.
Sometimes modern medicine just extends the worst parts of life. Keeping a body alive isn't the same as letting a person live with dignity. True compassion means accepting when the fight is over.
In my town, we had a similar case last year. But looking back, I wonder if the person was really past all help (you know, like therapy or meds). Sometimes pain clouds our judgment more than we admit.
The line you're confused about often comes down to personal dignity, not just pain levels. @gibson.elizabeth brought up help like therapy, but for some people, that help just drags out the suffering. Your aunt's situation shows how choosing control can be a final act of kindness, not selfishness.