These are the hard things of life...the things that make no sense this side of heaven. I still wonder why, I don't think there is anything wrong with asking God why. I think about them often...helpless to do much more than pray for them and send a note of encouragement from time to time. They say time heals...maybe...I think time dulls the pain but I don't think it takes it away completely.
My advice, for what it's worth..if you know someone that has experienced death of a loved one, acknowledge their loss, especially on those special days (birthdays, date of death etc) Trust me, they are already thinking of that person on those days, you will not make them feel any worse.
My other advice...live each day as if it were you're last...don't leave things undone or unsaid, especially when it comes to relationships. You would have thought I would have learned that lesson after this event but no...it took breast cancer to finally drive that concept home...what can I say I'm a slow learner.
"You will keep in perfect peace him whose mind is steadfast, because he trusts in you" Isaiah 26:3