Grief when they aren't actually gone yet

Does anyone feel like they have been grieving a parents death when they haven’t died yet but have had a health condition for a long time and you are very slowly watching them die?

I know exactly what you mean. My mum survived a stroke that robbed her of her speech and mobility. She was 5 years in a care home and in the end she was a tiny riddle of bones.
Only three years later, i ended up caring for my bedbound wife at home.
In both cases i felt i was grieving the loss of who they used to be and the lives we once had.

Yes my wife passed in feb with vascular dimentia which she had for 6 years so yes we do understand very much do ken oxford