About a half hour later, I said "I want nothing more than for us all to be able to hang out. But the fact that we can't is not because of me." W looked confused, "what do you mean?" "The reason you don't feel comfortable with him is not because of what Ive talked with him about. It's because of your decision." She nodded. "And when you make me feel like I am responsible for you feeling bad or awkward, it hurts my feelings, and makes me feel like the bad guy." She nodded. Then she said "I just don't like anyone ever thinking bad of me." I wanted to say "then don't do bad things" but I just said "I understand that."
Boundary set?
Maybe. Do you think she understood you were drawing a line in the sand? You threw some truth darts at her and told her how she made you feel. You got part of it down, anyway.
My question is how are you using a boundary here? A boundary protects you from something you will not tolerate. You obviously don't like it when she tries to make you feel responsible for her being uncomfortable. You have confronted her and told her how it makes you feel.
Sometimes it's not enough to just tell a person how their actions makes us feel. Especially when it is a man to woman situation, he can't afford to sound as if she weakens him. Sometimes we have to state what we will do if that boundary is violated. But whether the action is stated or not, you have to be prepared to follow through with some type of action if she continues to do what she now knows you don't appreciate.
I applaud you for speaking up about it. It's a beginning.
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!