When people are in the midst of grief, they often feel like they will never get over it. They develop a sense of hopelessness, like they are stuck in their grief. People do, however, get through the grieving process. Things will never be like they were before, but the intensity of the emotions will lessen with time. There is hope at the end of grief.
People do reinvest their lives and find new activities and new people to do things with.
Support groups have helped a lot of people deal with their feelings of hopelessness. Grief is an almost universal experience. There are others out there who are dealing with these same emotions and can share their experiences with others. People do get through their grief.