So the other day I was playing my Sims and for one family I have a single mother with two twin boys. Now the boys just recently grew into children which freed up a lot of the mother's time to go out on the town and strengthen friendships and relationships that weakened while she was busy taking care of the babies/toddlers. She was on her first date since having the kids and invited him to the house for the date. I noticed one of the boys crying and when I clicked on him it showed the mother sim's face and said "Cry", like he was trying to cry to her. After a moment he quit, but then as soon as he caught sight of his mother and her date again he started crying once more and I noticed his relationship points with the two adults had dropped dramatically.

I'd like to get other people's opinions on this: Why is he crying and upset about them dating?

My opinion is that perhaps he's upset she's on a date with someone other than the Sim who is his father. That's the only thing I can think of, unless he doesn't think she should bring dates to the house which I just don't think is likely. I do find it funny though that the other son doesn't seem to have a problem with this.

From what I've seen, your theory is exactly right.

Your idea would be correct. If a sim has a strong relationship with both parents, but the parents have broken up, and the sim sees anything (such as intimacy) between one sim parent, and another sim (who is not their other parent), they will cry, and be upset. As any small child would be.

A good point, but the father was only over the first day they were born and hasn't seen them sense. They do not even have a relationship rating with him.

So basically I'm correct in assuming it's probably linked somehow to it not being the father. I'm going to test the theory by inviting the father over right now and see how the child reacts.

Ah, in any case, if it's not the child's father, they will be upset. Regardless of relationship.

(and in other cases, if it isn't the child's mother...)

They stop caring as much once they transition to their teenage years.