FWIW I think the divide is probably between those who have experienced a major loss themselves and those who haven't. After my dad died, people who were comfortable with my grief tended to be those who also told me about their own loss (which was comforting in itself, I eventually came to feel that I had simply joined the human condition, such as it is). In your and Mozhu's case, though, I wouldn't be comfortable mentioning that death if I didn't know you as well because I wouldn't want it to sound like I thought it was comparable to you losing your spouse this early in your life, because it really isn't. So, maybe that's why the source of the divide is invisible to you?

It could also be that this type of loss is just more scary to people. When I told him Cameron had died, Ken said "I am having the world's most selfish reaction right now." Whereas I had already dealt with "what would happen to poor me if Ken died" at the time of diagnosis and over the next few months.