You do not control other people. Boundaries aren’t a tool to control someone else’s behavior; they’re a statement of what you will tolerate and what you will do when something is undesirable. A boundary says, “I refuse to do this” or “I will do this.”
A boundary is you stating that you will take an action in a given situation. That action can be inaction- “I won’t do that” - or it can be action - “I will respond like this”.
A boundary is “if you do that, then I will do this.” A boundary is “I will never do that.” A boundary is “I will only do this if we talk about it first.”
Not a boundary: “Stop talking about cats.” (this is a request, not a boundary!) Not a boundary: “I don’t like it when you talk about cats.” (this is a preference, not a boundary!) Boundary: “Please give me a heads-up before we talk about cats, or I won’t be able to have that conversation with you.” Boundary: “I won’t talk about cats with you.” Boundary: “I’d rather not talk about cats today. I’ll have to ask you to leave if you keep talking about.”
“No” is a word that must never be negotiated, because the person who chooses not to hear it is trying to control you.
Because I know that few American men have heard it, and few women have spoken it, here is what an unconditional and explicit rejection sounds like: No matter what you may have assumed till now, and no matter for what reason you assumed it, I have no romantic interest in you whatsoever. I am certain I never will. I expect that knowing this, you’ll put your attention elsewhere, which I understand, because that’s what I intend to do.
Gavin J. Becker, The Gift of Fear