I was very disappointed with the way sims mourn, to be honest. My first trial with dying in this game was such a let down. I had a family of four (two YA children and their elderly parents). In my story, father and daughter were very close, at maximum friendship, and both had family oriented traits. The daughter didn't witnessed her father's death, and I had to prompt her to view the urn to even make her sad, but that was it. A few hours later, and in the following days I never saw her cry or mourn for her father, and she never developed the sad moodlet on her own. I didn't see the son mourn either, beyond the day of the death, and he witnessed the father die. On the other side of the spectrum, in my asylum challenge, one of my sims (who was insane and hot-tempered) wouldn't stop grieving for another patient whom he was barely acquainted with. There was barely even a sliver of green in their friendship bar, no romantic relationship, and yet he's always crying over her tombstone.