This trait is on The Sims 4.
Not to get confused with the jealously trait.
These Sims get Jealous more easily than other Sims. They gain a boost of Confidence from being around their significant other, but get Tense if they haven't seen them recently.
All Sims can get jealous from romantic interactions going on around them, but Jealous Sims are more likely to feel this way even if nothing romantic is happening. While other Sims will have no major reaction to not seeing their SO for a time, the Jealous Sim will grow tense as if worrying about what they're doing.