I don't know if it's the same issue with me, but I have been experiencing the same thing. Until know I did not find a solution whatsoever. I hadn't played Sims 4 for a while, so I was aware that I needed to update the game and my mods / cc. So I did that. I looked through my mods folder twice and checked it with the better exceptions mod too, so I'm pretty sure by now everything is up to date. Still, whenever I load the game, after about ca. 20-30 minutes the game crashes. No matter the household size. I also checked with the Task Manager and first it seemed that I suddenly had over 90% CPU usage, so I looked up what I could do about that. Once that was taken care of, the Task Manager showed me instead a high RAM usage, so I tried to lower settings, and also went through services etc. But it all did not seem to help. It still is crashing. Since people with no mods have that issue too, I came to assume it must be the game.
Sims 4 shouldn't be that demanding to the system, I've played it for years basically at this point and rarely had issues. Also, the same computer is able to run other games. I didn't buy any expansion pack recently, so it should've come with one of the updates.
That's all I can say about it. I hope, there'll be a solution at some point.