"Cathedral" shows a distinct movement from dissatisfaction to satisfaction. The unnamed man who narrates the story oozes dissatisfaction from every pore at the very beginning. We can see that he probably loves his wife, but that the marriage is far from happy and healthy. His most immediate reason for dissatisfaction is the impending arrival of his wife's ex-boss and long time friend. His movement from dissatisfaction to satisfaction is most pronounced because the story is told through his eyes, but the other main characters undergo similar movements. The end of the story doesn't guarantee lasting satisfaction, but it does offer hope of happiness and meaningful connections to other people through creativity and broad vision.
"Cathedral" argues that intimate friendships can make the small dissatisfactions in life more tolerable.
It's likely that the narrator will return to his state of dissatisfaction after the initial excitement of his renewed vision has faded.