For me its not just the children. Sims also dissapear from my adult sims' relationship list. It must be sims met after a certain event because there is one non-houshold friend that doesnt dissapear. The sims that dissapear from the relationships list still exist and can be re-met later. It makes some careers and aspirations essentially impossible.
I have no mods.
Same here, sims are also disappearing from my young adult sim's relationship list. He met 3 sims, 2 were gone quickly, they're still in the neighbourhood though. I've seen this regularly in my saved games after the patch, didn't have troubles with disappearing sims before patching.
