First, realize that he is "out of character" for him. What he's doing now is not the man who won your heart.
As for wondering how much he could have to say to OW......one reason could be that he's giving her a picture of the man he wants her to belive his is. Remember that you already know everything about him.
I am M to a non-talker also. It used to worry me and make me angry that my H would not talk to me, but I have learned that I "can" accept him for being that way. I'd hate to think he wanted me to change from my talkative personality to his more non-verbal one.
Sweetheart, I will try to answer whatever question you might want to throw my way, but for the most part....I won't be able to answer most of them.
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!