In a way Covid may have been a good thing for the Queen ,with so many events cancelled she could spend so much more time with him before he died, glad he could die at home, it means so much. I can't begin to imagine what it feels like to have loved someone from the age of 13 and them to be gone and even when it is expected it is still so painful, and yes when someone you love has been ill for so long there is a sense of relief, and guilt for that relief.
The other thing is The Queen has a strong Christian faith so she will have hope to be reunited with him one day. I envy her that.