At what point do you break up a couple?

I began 'Simming' in 2005 with Sim2. Since that time I can count on one hand how many divorces I have allowed in my game. I play my values. However, my singer Sim broke off two engagements before he finally tied the knot. Then, to his deepest regret, he ended up divorcing her after the birth of their baby boy. She was obnoxious and was abusing the baby. All of this was done autonomously. When she did it a second time, I had my Sim race home immediately after his gig and rescue his infant son. They fought again, and I guess they never truly mended their relationship after the first big row they had. The ability to 'break up' was on the menu. I sat back in my desk chair, hesitant, for only a moment. I realized the best thing to do was for my singer to choose his son over his wife. I clicked 'break up.' Then I paused the game, and went immediately into Edit Town and pulled her from the household and placed her in an apartment. There was no way I was going to allow that evil witch custody.