Not to make this about me, per se, but to illustrate the different circumstances of losing parents (or other loved ones):
My mother died suddenly (although she had been in poor health) 25 years ago.
I still remember getting the phone call at 7 am, and my dad saying, "please pick up, please pick up," into the answering machine.
He had awakened to find her gone.
It was early January. The last time she called me was a week before, on New Year's Eve; I had forgotten or neglected to call her back. Typical conduct for a jerky single guy.
So I've always been haunted that she died thinking I didn't care. I still have the answering machine tape; the last words she ever spoke to me.
My dad died seven years later, after about a 6 week decline, with the last couple weeks in hospice. The last week or so was pretty rough.
For a couple weeks my siblings and I got into a rotation schedule so somebody was always with him. It meant a 200 mile round trip for me every other day; I didn't care.
When he finally went, the two of us there were me and StarSis of kids' sports fame. His oldest and his youngest. We held his hands as he went.
It hurt to see him go but I didn't have to worry he might have thought I didn't care.
A couple hours after he went, all of us actually had a pretty good lunch, with a lot of joking. None of us had been eating well for weeks and we were all starved.
Of course we all knew what had happened, but we also knew his pain and suffering and confusion were over.
I think back now on seeing my dad die: it wasn't awful, it was peaceful. A couple moments before he went, we told him we'd be fine. He looked at us both and nodded. Then he just seemed to go to sleep.
When my mom died, I had to drive 100 miles to get home. I arrived back at the house just as they rolled her out. I hardly ever want to remember that again.
So it's certainly very different to lose someone suddenly as opposed to knowing it was coming.
On the other hand, the people I really feel for are the people who have to go through months or years of end-stage care for their family members with little hope of improvement.
I'm grateful that none of my relatives have had more than a month or so requiring constant care; even my 99-year-old grandmother was really only bad for a couple weeks.