When we lose somebody who was close to us, when somebody we loved has died, our world changes. It feels like nothing is going to be the same. It might be the most demanding change one can face, full of emotions that can be very irrational and very strong.
This article includes a widely known psychological theory of loss and grief, and the phases our mind goes through after a loss. Maybe it will help you to better understand yourself or people around you that have lost a loved one.