The author's point is that grief is now being diagnosed as a "mental disorder". Grief. We lose something, someone we love, we grieve. That is what it is to be human, to feel.
I think of Rilke's words in Letter to a Young Poet:
If we only arrange our life in accordance with the principle which tells us that we must always trust in the difficult, then what now appears to us as the most alien will become our most intimate and trusted experience. How could we forget those ancient myths that stand at the beginning of all races, the myths about dragons that at the last moment are transformed into princesses? Perhaps all the dragons in our lives are princesses who are only waiting to see us act, just once, with beauty and courage.