Mike,
If I am stepping in areas that are too sensitive at this time, please forgive me.
The loss of your grandson Luke is a great loss. Highly evolve people (souls) are here for only a short time; they are "old souls" in the highest levels of spirituality, love and selflessness. I suspect that Luke was one such soul.
Way back when, when he first incarnated into your family, he knew that he would leave this plane soon, and that was his life purpose, and another deeper purpose that is unfolding now as a result of his selfless death. His gift of himself. Deep in each of us, we all know these things before & when we are born, it is just not something that we discuss with one another about during the course of our daily lives.
We all have different spiritual philosophies, but what I am certain of is that we are spiritual beings in physical bodies. This is so temporary for a fraction of what we measure as time.
I know that does not lessen not having Luke around, seeing him, interacting with him, talking with him , or having him there as part of the family at meals, going to school, etc. But he is there, ALL AROUND YOU.
This is mean to be a small & compassionate understanding as to "the why" these things happen.
With My Friendship & Prayers... John Weiskopf