OK, granted Logic, she knew he is married. But I have lost count of the women (and men) I have known who have got involved with someone who is married and been told the above only to be left. Boils down to the same thing. He wants his cake and to eat it. Wants the bit on the side, keeps her sweet with "I miss you, I love you, my wife doesn't understand me". Some women are stupid enough to believe it (I have been there, although wasn't stupid enough to believe it and there were enough warning signs for me to know that I was being used so bailed out).
Sounds to me like he wants his fun with his mistress but will NEVER leave his wife.