The decision "If she PAs, I will divorce her" is a boundary. It controls Peter's behavior.
The announcement "If you PA again, I'll divorce you!" is not needed to control Peter's behavior nor to enforce his boundary. The primary reason he would tell her is to attempt to influence or manipulate her.
Originally Posted by HappyPanda
Most boundaries (yours and other people’s) aren’t explicitly stated. Usually, there’s no need to voice a boundary unless it’s overstepped or violated.
Originally Posted by GoodMenProject
When you cause a person to act out of fear—the fear of retribution—you turn that person into a slave. Threats make people give in to your demands when they don’t want to, because you make the pain of refusing greater than the pain of giving in.
This is why there are little to no recons here. Bad cookie cutter advice. Set boundaries, set ultimatums. This is hard, but, it helps avoid all the back and forth. Does she want to be married to you or not? Thus far she said she wants a separation or a divorce. Act on that. If you want something else, state it. You can say, "If you want to work on this marriage, fine, if you don't, I have some decisions to make in the next few weeks." Strength and clarity are attractive.