Affair

An affair happens when a Sim in love with another Sim interacts romantically with a different Sim.

Getting Caught


Having an affair can be risky as getting caught can possibly ruin the relationship with the other Sim.

Ways a Sim can get caught:


 * WooHooing on the same lot as another lover passes by, even if they're on opposite sides of the lot.
 * Going on a date when the other lover enters the room.
 * A lover sees the flowers a date may have left (though an apparent bug in TS2 means flowers sitting on a shelf or other surface might go unnoticed).
 * A child who sees the adulterers mid-WooHoo may tattle.
 * Sleeping in the same bed when your lover is around.
 * Doing any romantic interaction to another Sim while the lover is around.

Interestingly, Sims can be caught cheating by the ghost of a deceased Sim with whom they had a romantic relationship before that Sim died. The ghosts can even become furious with the Sim who cheated on them.

Getting caught by children

If they catch their parents cheating, they get the same relationship decreases, and if left to their own devices, may even attack their own parent or who the parent is having an affair with. They don't get any visible memories from this aside from any meetings, but effectively act like a Sim who has been cheated on. They'll either cry or get angry at the parent. However, if one of their parents had died and they somehow didn't know about it, it could cause needless drama if they consider looking for love again as cheating.

Jealousy
Whenever a Sim, who has a crush or is in love with another Sim and watches the latter partake in some romantic interaction with another, fury occurs. This doesn't take into account whether the feelings are one-sided or not, which may be messy for unrequited crushes. It may even still cause some kind of jealous reaction if the flirting is done by someone else and rejected, though it's not really confirmed.

The witnessing Sim often loses the crush or love marker, and his or her relationship with the cheater and the one he or she's cheating with plummets into the negatives (if he or she doesn't know the other person, a "Met Sim" memory is added along with the affair and possible "Fell Out of Love" memories). In Nightlife, this also triggers fury, and it tends to last quite a while. This relationship drop enables breaking up, assuming the Sims were going steady, engaged, or married.

The cheated on Sim will reject the cheater should they try to interact with them romantically.

Repairing relationships
Getting caught in an affair won't always spell the end of a relationship, but it can make bringing it back up extremely hard, especially if the seconed Sim is more interested in fighting with the other one (this could cause the other to lose their own Crush/Love markers, and even trigger Fury to make things that much harder).

To apologize for an affair, select the cheater and click on the spouse cheated on and select Appreciation/Apologize from the pie menu, but only after the fury or "Betrayed" moodlet has ended, if not, the betrayed sim will not accept the apology. It is easier to repair relationships if the Sims are BFF's, if the Sim uses the "Smooth Talk" interaction, or "Repair relationship with..." interaction after studying "Couples Counseling".

If a couple somehow manages to get tarnished by an accidental affair, it may be best to use cheats or hacks, such as InSimenator, to fix the problem, or exit without saving.

As well as repairing jealousy, there is also a way to prevent it. In The Sims 3: World Adventures, a new Lifetime Reward is added; No Jealousy. This reward costs 10,000 lifetime happiness points. If your Sim has this bonus, Jealousy is eliminated altogether! They could be flirting with another Sim right in front of their lover's eyes and they wouldn't care! The No Jealousy reward also makes it possible to create a polyamorist Sim, with multiple lovers living under one roof.