From my husband's perspective this is the information I got--
The father feels responsible for their child's death regardless if they could have prevented it or not. As the head of the house, as the man of the house, as the protector of the family they often feel responsible for the loss of the child. They did not protect their child from harm ( or illness, etc), somehow they should have been able to do so. The father is the strong one in the family, made to keep his family safe and this can result in a lot of guilt or shame or pain if a death results.
The holiday is not one they really want to celebrate since the family isn't whole. It is not that they do not love their children that are remaining but during this holiday (and most) it becomes terribly obvious that the child is gone. It is very apparent to all of us in the family that DJ is not here to celebrate with his Dad.
What does a father want for Father's Day? He wants to hear about his child. Phone calls, conversations, notes, cards, memories about their child is the best gift. To hear something wonderful about their child that is gone is the best gift of all. Do the father's ever ask for this? Of course not...do they wish everyone knew about this request? Absolutely!
So what are you going to give a bereaved father this weekend? A memory, a humorous story, a laugh, a cry? The mention of a father's child is the best gift of all!