From Harvard Health (https://www.health.harvard.edu/mind-and-mood/long-lasting-grief-when-close-friends-pass)
Losing a loved one is never easy, and sometimes it can take years to grieve for a partner, parent, or child. That grief often comes with adverse health effects, such as stress, depression, insomnia, high blood pressure, and heart problems. But long-lasting grief doesn't come only from a family member's death, suggests a study published online April 4, 2019, by PLOS One. Researchers evaluated questionnaire responses from about 9,600 people who'd lost close friends and found this type of grief can last up to four years. Women in the study were particularly hard hit by loss of a close friend, experiencing more problems with mental, emotional, and social health than men. Study authors say the passing of a close friend should be considered a substantial experience that warrants help (like a support group) to minimize the negative effects of grief.
Our take: Grief of any kind poses a health risk, whether it's due to the loss of someone dear or a dramatic change in life, such as a job loss or a move to a new city. During such times, be especially vigilant about reporting disturbing new symptoms to your doctor.