Thanks for the posts lMo & Kathy.
The main positive I see out of this is I am getting some 3rd person advice and by explaining my situation more fully (which it seems you folks have read and I thank you for taking that time) I am feeling more understood.

LMo: I agree there's nothing wrong with going to a marriage counselor. I've been looking up some of the local ones for me to go to, on my own, if just to get a professional perspective on how to proceed.
And I do agree, this may partially be my doing. I've been examining and re-examining my own behaviors trying to figure out if there's something in our relationship which is encouraging her to look elsewhere for intimacy.