Receiving Notifications & Getting Sad Moodlet When NPC Sims Die??

I noticed that happening to me last night when I was Simming. My Sim made some relationship progress with an elder neighbor. Then suddenly in the middle of the night she got a phone call stating that Sim died and on came the sad moodlet. :o I also noticed that if a Sim becomes less of acquaintances with another Sim, they disappear from the relationships panel and would have to meet them again if I wanted them to become friends. But any with just a little green stayed.