prolonged grief disorder

PSYCHIATRY

An abnormal grief reaction that follows the death of a loved one which extends well beyond the usual–6 months is a common benchmark–time frame for bereavement.

Depending on the stringency of applied criteria, up to 10% of bereaved survivors suffer from prolonged grief disorder. It may respond to tricyclic antidepressants and time. While diagnostic criteria had been proposed for PGD, the poobahs who penned the final draft of the DSM-5—Diagnostic and Statistical Manual, 5th edition felt that PGD is not a disease a sui generis. 

Synonym Chronic grief syndrome 

Reference https://en.wikipedia.org/wiki/Prolonged_grief_disorder