JM and I both had this issue, and while the behaviors were the same on the outside, our innermost "why" was different. Also, it was extremely difficult for me to admit that I struggled with boundaries, and I caused him a lot of pain and worry that was totally unnecessary.
For myself, it was incredibly important to me that I have the upper hand in every relationship. I was always the smartest, the most "put-together)" (ha!!) and gravitated to people who needed help. People who were worse off than I was. I felt very powerful (looking back) when I was needed, and it became almost impossible for me to respect/recognize appropriate boundaries because "What if I say no/maintain my distance/not hug this person back and they go off and do something awful to themselves. It would be my fault." The truth is, that probably 100% of the people I crossed boundaries with would have found another sucker, I mean savior, within seconds.
JM was also a KISA, but his behavior came more from a place of fear and needing people to like him. He could not stand for someone to be angry at him. Particularly if that person was in his face or on the other end of a phone. He would say and do whatever he had to do IN THE MOMENT to keep peace and keep the other person happy.
For both of us, living so completely in the moment, we could not process potential consequences. Looking back now, it seems so freaking stupid. How could he not know I would be angry later and he'd have to deal with that? How could I not know that eventually, when you say yes to everyone you are not powerful but pathetic?
All I know is that it has taken a butt load of work for both of us, but we now recognize that our relationship with each other, our boys and our personal relationship with God are the only things in life that really matter. And every decision, no matter how small, is evaluated on how it will reflect or affect those primary relationships.
Toasted, you have to find the ability to face whatever it is you fear will happen when you enforce a boundary in favor of your W and your M. One question that sticks out to me is this: You said you broke "a" boundary. You broke "a key boundary."
Whose boundary is it? If it's your W's then that's a big part of your answer right there. Your boundaries need to be YOUR boundaries. It needs to be unacceptable to YOU to meet with a female one on one that is not your wife. Not because it will bother your wife. But because it's abhorrent to YOU. You betrayed your wife and caused unimaginable pain to her. You betrayed your profession and caused potentially irreparable damage there. You should want to change your behavior because you don't want to be that kind of person, not just to try to fall in line with your W's expectations for R.