Part 2 is now out here.
My cat died on Tuesday. She may have been a manipulative psychopath, but she was a likeable one. She was 18.
On that note, here's a paper about bereavement.
It's been recognized since forever that clinical depression is similar, in many ways, to the experience of grief. Freud wrote about it in 1917, and it was an ancient idea even then. So psychiatrists have long thought that symptoms, which would indicate depression in someone who wasn't bereaved, can be quite normal and healthy as a response to the loss of a loved one. You can't go around diagnosing depression purely on the basis of the symptoms, out of context.
On the other hand, sometimes grief does become pathological - it triggers depression. So equally, you can't just decide to never diagnose depression in the bereaved. How do you tell the difference between "normal" and ...