@Gednaa I had the exact same thing happen to me! It was my first emotional death after YEARS of playing the game. He moved in after a marriage and immediately died of laughter (I guess he had such a good time at the wedding?). I had tried in the past to get emotional deaths to trigger but never succeeded... go figure lol. I was able to restore a previous save for the unintended death, which is something everyone can do up to a point automatically.
You can also, if you notice it, sleep off the emotional effects if you're not able to do the other things to bring them down. BUT you have to catch it before it's too late!!