At what point do you break up a couple?

I broke up a couple with one child because they seemed to belong in different worlds. They didn't live together to begin with, but I had plans to move them together. The girl decided she wanted to stay in her parents' place in Willow Creek. The guy was originally from Willow Creek too, so I didn't expect there to be problems, but he had moved to a tiny house on Windenburg island and really liked it there.

I don't mind some drama, but in rotational play it takes so much planning who ends up with who, so usually the couples stay together.