Grief is something that is sacred, spiritual and specific to each individual. To overcome grief, some people turn to family, some to drugs or alcohol. Some people keep busy, while others do nothing at all. Some people need to cry, others need to laugh.
Grief is one of those emotions that drives people to the depths of their emotional capacity and most of us simply don't know how to deal with it.
That being said, it can be difficult for one to relate to how another person chooses to grieve. While we might expect someone to react in a certain way, that may not be how that individual needs to cope with an emotion as complex as grief.
Sometimes when one grieves their usual strength and tenacity takes a back burner. Someone who is emotional may shut down completely, seeming almost unscathed by news that should make them saddened or distraught. Someone who is stoic may break down, falling into depression. Someone who relies on others may end up becoming a pillar of strength for those they previously depended upon. Someone who is happy may become angry or violent.
Our role in situations where people are grieving is to recognize and respect that each of us will deal with grief in a different way. We shouldn't judge others for how they choose to grieve because we interpret their choice as callous, insensitive, inappropriate, weird, maddening, immature, or whatever; a judgement call of that magnitude is outside of our realm of understanding.
Be caring and considerate of people who are grieving. You simply can't understand how someone else experiences and deals with grief. Judging someone for how they grieve is, in effect, invalidating their grief.
No one wants to have their emotions invalidated, especially with one as deeply personal as grief.