I think that the relationship between husband and wife is a complex one. On the surface, it is quite a dominating relationship in that she is controlling and he is very submissive. She is the one who "nags him to buy galoshes, to put on his gloves, and to drive more slowly." For his part, Walter flees into his world of dreams, in part to escape from elements of reality that he finds undesirable. Mrs. Mitty is one of those elements. Walter's flight into dreams is due in part to the fact the he can never be anything more than an ineffective husband whose wife has to look out for him.
However, it might be here where the relationship between both is complex. Walter is only saved, to a great extent, because of his wife He is the Quixote- like figure who is able to retreat into dreams and into the world of the subjective. She is the Sancho, worried and concerned with the mundane. The day to day existence, a state of being that Walter cannot handle, is one element that she is able to take for him. Put another way would be that Walter is only able to dream because his wife is there to ensure that his reality is not one in total chaos. In this light, they make a complementary pair. Walter might not want to admit it, but his dreams and her focus on reality are where they function as a couple. He probably needs her more than she needs him and more than he realizes.
This is a hopeful read on their relationship. The reality is that there is a disconnect in their relationship, indicated with his line, "Does it ever occur to you that I am sometimes thinking?" While her response is classic in the "I will take your temperature when we get home," Walter faces the firing squad alone and, in his mind, with courage. His wife is not by his side as he stoically and heroically achieves a summit in his own mind.
Carl Jung, the famed psychoanalyst, coined the terms “introvert” and “extravert” in his brilliant book Psychological Types. Walter Mitty is obviously an introvert. According to Jung:
The introvert sees everything that is in any way valuable to him in the subject; the extravert sees it in the object. This dependence on the object seems to the introvert a mark of the greatest inferiority, while to the extravert the preoccupation with the subject seems nothing but infantile autoeroticism. So it is not surprising that the two types often come into conflict. This does not, however, prevent most men from marrying women of the opposite type. Such marriages are very valuable as psychological symbioses so long as the partners do not attempt a mutual “psychological” understanding.
Examples of how Mitty “sees everything that is in any way valuable to him in the subject” can be seen in all the episodes in which he is fantasizing about doing heroic or noble deeds. They are all triggered by objective reality and then translated into subjective experiences. For example, his wife tells him he should see Dr. Renshaw, and he quickly begins imagining that he himself is a distinguished surgeon. Mitty pictures their family doctor in his fantasy as “haggard and distraught.”
“Hello, Mitty,” he said. “We’re having the devil’s own time with McMillan, the millionaire banker and close personal friend of Roosevelt. Obstreosis of the ductal tract. Tertiary. Wish you’d take a look at him.”
As another example, Walter Mitty is driving to town and notes that it looks like rain, and he becomes Commander Mitty piloting a hydroplane through hurricane weather. The object becomes subjective.
Jung seems to be saying that most introverted men marry women of the opposite type. Or else he is saying that introverts and extraverts can have successful marriages. At least we see many marriages in which the husband is quiet and introspective while his wife handles all the domestic and social arrangements. If the Mittys have a “symbiotic” relationship, what does Walter contribute? He is probably the one who earns the income—although it is his wife who spends it. He is the only one who can drive a car. Her concern about her husband may be largely a matter of dependence. Even her social life would be crimped if she were a widow rather than part of a couple. And this would be a serious matter for an extravert.