Even when he decides to stay in the marriage, he doesn't want to confront his wife about the things that have hurt him and led to the affair. Now she is the hurt party and he doesn't have the right to say what he needs. Only when his needs are addressed does the marriage have hope. Men are learning to work around the weaknesses in their styles of interacting. Introverted men are often more comfortable with distance that can hide their real capacity for engaged conversation.
Quiet men can learn to take time to process their thoughts.
A wife tells her husband she would like to discuss the movie they just saw. He says ok but not right now. The next day he thinks about the movie and has lots to say at dinner. Men our age are easily depressed and need to watch that they are not depleting themselves by working too hard or doing too much of the same thing over and over. One depressed engineer goes to culinary arts school to cure himself and finds the cooking more filling than the eating.