What was the sim's emotion at the time? Tensed/stressed/angry/etc will tend to trigger certain behaviors. But at most my sims will usually just shout forbidden words in frustration in general and not towards anyone specific. Does he have any negative sentiments towards the wife (I know you said she's smitten but he can have different ones)? Knowing his traits might also help.
The father yelling at the son makes sense if he still has the hurt sentiment (that will take a certain amount of time of keeping the sims away from each other to avoid them accidentally making it worse, or apologizing a few times). But I don't understand why he would at the wife.
