Not that straight forward really. Just so you know, autonomous slapping has come back with this trait. If a sim's 'Significant Other' flirts with another sim the jealous sim will walk across the room and slap his/her partner/spouse. This slapping will occur if the significant other is flirted with and rejects the flirt too.
There are actually a lot of new situations where this (and autonomous berating) will occur as the patch that brought us this trait has changed how jealousy now works in TS4. This trait actually has added quite a surprising amount of change to the game when it comes to partners/spouses etc. The sim with the jealous trait will get a variety of moodlets across a day:
Sad +1 Envious:
It's hard to see other couples together when you don't have anyone special in your life. (This occurs with single jealous sims)
Uncomfortable +1 Jealous Pangs:
It's not always reasonable, but sometimes those jealous feelings just come to the surface. (Usually occurs after the jealous sim sees his/her partner just talking to another sim)
Angry +3 Jealous Fury:
Hell hath no fury like a scorned jealous sim. (Occurs after seeing partner flirting or being flirted with)
Tense+1 Feeling Insecure (lasts 24 hours if the jealous sim doesn't see the partner/spouse. As soon as the jealous sim sees or talks to the partner the moodlet begins to count down rapidly)
If your significant other isn't around how can you know what they're doing...and who they're doing it with?
Confident+1: All Mine
No need to feer, "Sim's" significant other is near. (Randomly occurs when in the same room as partner)
Jealous sim children can also get jealous or sad when they see their parents kissing etc.
Single sims with the jealous trait will get a sad moodlet when around other couples because "they don't have anyone in their lives"
