We all grieve in our own way and time.
I imagine the Queen finds doing her job helps, otherwise she could have handed looking after the visitors to Prince Charles.
Bear in mind that we have only ever seen the public face of her marriage. It may have been wonderful and the loss immense, but statistically, it is far more likely to have been a perfectly ordinary marriage with its ups and downs, disagreements and times of deep content and happiness.
However at the Queen and Prince Phillip's ages I expect they had both long since faced up to the fact that one would be left when the other died.
That doesn't make loss easier, I know, but it does suggest some level of preparedness.
Lack of public toilets in towns.