It depends entirely on where you are in your relative cycles, and the duration. My mom grew ill right as I was getting married and moving across the country. It would have been insane to expect me to care for her. My father was her primary caregiver for 10 years, until she died. 5 years after that, my husband and I were both retired and living in the Caribbean. When Dad got ill, I went to care for him, for his final 4 months. The idea wasn't that I would be there that long, but would help him transition to a situation where he needed care help. Except the situation kept shifting so quickly, there was no way to plan a transition. We never had more than 1 meeting with a support person before we had to start over.
I'm glad I was able to be there for him, because the support services that we expected to be there failed utterly. But if it had been earlier, while I was still working, it would have been a different story.