Okay, I think I understand. For clarification, stating a boundary is not the same as having a discussion about the relationship. However, I can see how that might sound contradictive. Having R talk is when you are trying to fix the MR though talks, which the majority of LBH'S want to do.
Whenever you state a personal boundary, it is not with the intent of starting a dialogue. It is to establish her awareness of where your boundaries lie. You state it, then leave her with it. That's all you are doing, is telling her how it makes you feel and what you will have to do to protect yourself.
An example: "When you have private contact with _______________, it causes me to feel ______________. Therefore, if you continue, then I will _____________".
The link on boundaries can probably be more helpful than I am.
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!
