Dreaming of digging a grave with friends symbolizes loss, disappointment and the death of personality.
scientific explanation
Dreams are residual activities of cerebral cortex, which can better reflect psychological changes in daily life and even physical health. For example, dreaming of a green snake when you are sick often represents a decline in physical function and aggravates your condition. But dreams can't reflect your fortune and career, and there is no way to express any future situation of others.