Hotpepper ...
Extremely sad. This virus thing is affecting us in many ways.
If I can offer a perspective that may not resonate with some, but through experience:
Back in the late 1970's, my grandparents were alive, I was a teenager. My grandfather (elder) died from a stroke in his mid 80's. My grandmother, a lifelong colportuer / pioneer died a week later. I guess it was a heart attack, stress or the acceptance that it was the end.
As my grandfather once told me, he could not remember not being married to my grandmother (he was 17, she was 18 getting married).
It may very well be that there was a great deal of love between your parents. Not having that person at his/her side may have been an incredible burden.
I wish you and them forever peace.