It is not just you, it's become a common problem for most of us who play in a way that keeps our sims happy.
See this very recent poll thread for input from other folks complaining about the same thing: https://forums.thesims.com/en_US/discussion/952454/do-you-like-the-emotional-deaths#latest
I was having the issue a lot, every time toddlers were in the household, didn't even think of the fact that the goofball trait could cause spontaneous hilarity. Thankfully I turned emotional deaths off with a mod before the current generation, because one is a goofball.
In respect to your desire not to use mods, you'll want to just make sure to limit just how happy you let your sims get, until (if ever) the devs address this problem.
