Actually, I just thought of a rule that my domestic partner has with their other SO. That rule is - the topic of myself and Spouse breaking up is not up for discussion. This is OSO's first "serious" non-cheating relationship with a person who is already in a relationship. Spouse made it explicit to OSO that this is not some "transitional period" such as people sometimes do when they're in the process of becoming un-involved. OSO is "not allowed" to badger or suggest to Spouse that Spouse and I ought to break up.
However, this is not something I required or asked Spouse to do. It is something Spouse did of their own accord because that's how it is.