Very astute comment, Tom. I ha ve similarly struggled in the past, but I think for me, the key difference is that ultimatums are about controlling someone else’s behavior (e.g., “Do this, or else,”) while boundaries are hunky dory until someone bumps alongside them, and then it’s about communicating how you do and do not wish to subject yourself to treatment (e.g., “Here are the consequences for someone doing this thing to me, because I will not allow that treatment.”)

Does that shift things for you?