If you like simple endings that give you something to think about long after the story is over, you'll appreciate the ending of "Cathedral." It's this simple: Robert and the narrator finish drawing the cathedral. Robert tells the narrator to open his eyes. He doesn't. He feels good about the experience. The end.
We don't know if the feeling will last, if the narrator will continue his relationship with Robert, or if his relationship with his wife will improve. For now, the important thing is the moment, and the complexity and the simplicity of his experience.
Here's what Carver says about the ending in an interview with Claude Grimal:
CG: Could you talk about the endings of your stories? The ending of "Cathedral," for instance?
RC: Well, the character there is full of prejudices against blind people. He changes; he grows. I'd never written a story like that. […] Then, when I wrote that story, I felt it was truly different. I felt a real impetus in writing it, and that doesn't happen with every story. But I felt I'd tapped into something. I felt it was very exciting. The sighted man changes. He puts himself in the blind man's place. The story affirms something. It's a positive story and I like it a lot for that reason. People say it's a metaphor for some other thing, for art, for making . . . But no, I thought about the physical contact of the blind man's hand on his hand. It's all imaginary. Nothing like that ever happened to me. (source)
We agree with all of that, though we think Carver leaves out what we see as an important aspect of the ending – what it means for Robert and the narrator's wife. As we discuss in "Characters," Robert and the woman are also going through rough patches in their lives – the woman's marriage is in a bad place, and Robert has just lost his wife.
In the reality of the story, the woman's main problem is making sure Robert is "comfortable" (1.52, 54). Robert's comfort, she knows, depends on the narrator being nice to him, and she doesn't trust him to do it. Robert's problem is the same as the woman's, in a way. He's just lost his wife, and is in the area visiting her family. Surely, he's in as much need of comfort as the woman thinks he is.
The narrator delivers. He helps Robert feel comfortable. In spite of his discomfort and jealousy, he focuses on Robert, and does everything he can for him. The narrator even wants to make sure Robert understands what's on television. He rises above himself, and is rewarded in a big way.
For Robert this might be the difference between a night that increases his loneliness and sadness and a night that gives a genuine connection with another person. Only after the story is over will the woman understand what has happened. Knowing that her husband can connect with the person who seems to be her oldest friend and confidante might help heal the marriage. Just as the narrator learns to see blind people in a new way, she might learn to see her husband in a new way. The fact that the narrator is learning, through his experience, how to express himself when he can't find words, might help him express his feeling to the woman. These characters can become bridges to each other's happiness and healing.