Loss
Grief
a feeling of profound loss
Mourning
The external expression of grief through ...
rituals
including funerals
for remembrance
for saying Goodbye
...
specific behaviors
sharing memories
...
...
The shared, social response to loss.
Grief vs. Mourning
Some make the disctinction as follows:
...
The Cambridge Dictionary does not make this distinction, however.
Grief:
"very great sadness, especially at the death of someone" (Cambridge Dictionary)
Mourning:
"great sadness felt because someone has died" (Cambridge Dictionary)
Sorrow
Causes
mourning is destructive only when mixed with guilt, shame, helplessness
Summary
this can be very different from person to person, but there are patterns
How much externalization do you need?