Grief in a dream usually reflects a loss you're actively processing, whether that's a person, a relationship, or a version of your life that's ended. The dream can be an unusually direct space for that processing to continue, letting you feel and let go of something at a pace your waking mind hasn't allowed yet.
Be not too confident either of a Sextile or Trine Aspect in violent Signs, nor out of those Signs in which the Planets behold one another, yet essentially suffer. - William Lilly (1602.-1681.)