Could someone give me some information about Cheating?

[Deme]

What it says on the tin, really. I have a sim who I'd like to try out a wide variety of romantic options, collect some romantic interests, engage in a lot of casual make-outs, etc...But I'd also like that sim to have a shot at maintaining a recoverable (I don't mind the occaisonal dip and fight) relationship with a romantic interest/boyfriend she lives with.
 So, before I start taking action, I'd like some information about what the game considers cheating, two-timing, etc. I know the information's not going to be 100% due to just the inexplicable nature of The Sims 3, but I'm curious about what sort of things qualify as cheating or betraying, what sort of limits there are to it, how to repair damage after a sim gets found out cheating, how to avoid getting caught... My sims are usually all-faithful types, so I have no idea.
Basically, if anyone has some knowledge or stories, I'd like to hear them.

Or I could just do no jealousy/above reproach, but that's kind of dull. Maybe later, when things stabilize.

[sammymcgoff]

Kissing or making out when the boyfriend is nearby

[Turoskel]

I've only ever really played a proper affair once in game, I got away with it for quite some time by being careful, the husband was a policeman, the affair a sports star so in the mornings when husband was at work she went to visit the affair and then got home before the husband did.

If any messages come up that people have noticed something is up between your sim and one of their partners it's time to cool it off a bit, too many visits close together to their house or them to yours and people will notice, try not to be too romantic in public with anybody, even your legit partner or one of the affairs might get wind of it and dump you.

Unfortunately my sims marriage went really wrong when she had a baby by the affair, once the husband found out there was nothing I could do to stop him divorcing her, he just would not be civil at all and once they decide to accuse of cheating or reject you the game wont let you cancel it 

I think with Uni it might be a little easier to be more casually flirty using the juiced kissing options, they might not have the jealousy associated with them like the normal options do.

[rarespawn]

I've never done it on purpose in my game, but I think the game is a little overzealous about cheating.

I once had a family that had two daughters, and each daughter grew up to marry their invisible friend.  I was playing along like normal when all of a sudden I noticed the relationship bars between one of the daughters and her husband (imaginary friend) was completely red, as was his for her.  To this day I still have no idea what happened.  I think maybe he kissed a house visitor or something when I wasn't paying attention. 

But no amount of friendship potions or trying to interact positively could save the relationship.  I could get the relationship back into the green, but it would immediately fall again whenever they interacted and I wasn't controlling every part of it and making them talk to each other.  I ended up having to go back to a saved game.  I would say be very very careful, make sure you do a back-up save in case of horrible failure, and don't do anything in public! 

[RainBeau]

You can't cancel the 'Accuse of Cheating' action, but you can reset one of the Sims involved and that will cancel it.

[Deme]

It sounds like, when I want the relationship to become serious, I may consider hooking up both sims with stuff like above reproach and no jealousy, but keep it casual in the meanwhile. They're only romantic interests at the moment.