My mum regularly forgets dad died in August, they celebrated their 70th wedding anniversary in the June. It was OK for a week or two and then she started forgetting he had died and would be distraught saying nobody told her. Good news is that it has got quite a bit better, she still forgets but when she remembers she no longer has a meltdown. Sad thing is that she now also forgets that her son has died (7yrs ago now). She always knows who he is when she sees a photo but regularly forgets who I am. Still she doesn't get distressed for long if she remembers he has died.