It's funny, but despite an update many months ago, this problem simply returned.
Personally, I can't throw my sims a party of any kind without switching between eight sims, controlling whether they are flirting or someone is flirting with them. I won't give every Sim the Loyal trait, because they should have it installed in those digital heads.
There better be an "unfaithful" trait or something, because - let's be honest - it's sick that in a life simulation most Sims cheat on themselves rather than be faithful to each other.
