At what point do you break up a couple?

I have not encountered problems with my married sims couples, as I make my sims wait a long time before I let them marry - so it has not came up. Usually if there are issues and they are not very compatible I see that long before they go to say "I DO" - and if there are issues then there will never be an "I DO" for that couple. I sort of just let them drift apart - so that way there are no hearts broken and no children involved. I do not allow my couple to try for baby until they have been married a while and both seems to get the thought bubbles for babies and such.

I want no part of children upset over parents breaking up - so I avoid the issues before they can occur.In fact I will not even let my couples get a pet until they are right for each other - I don't want their pets upset either. LOL.