Your post seems to have hit the nail on the head. It is heavily implied that Shoba and Shukumar’s marriage came to an end after the story finished. However, I prefer happy endings to sad ones. I’d like to believe that Shoba still loved Shukumar even after the miscarriage,and that she simply made a poor decision in trying to deal with the grief by herself. An example I think supports my theory resides in paragraph 22, when Shoba goes to the nursery (Shukumar’s den) and tells him not to “work too hard”. Although the text explains that “it was something she forced herself to do,” I think it’s a routine that’s uncharacteristic of her. If she spends so much time avoiding Shukumar, why would she go out of her way to the place she dreads most just to try keep up the illusion of a functional marriage to Shukumar? It is also noteworthy that the story is told from Shukumar’s perspective so he may not have clear insight into Shoba’s mind.
From your post though, I’m interested to learn more about the “subtle way [Shukumar] lets [Shoba] down.” Aside from the seemingly obvious facts that he is “still a student at [the age of] thirty-five” (Lahiri 9), has made the nursery his office, and, to Shoba’s knowledge, was absent during her miscarriage, I’m unable to find any other reasons Shoba might hold a grudge against Shukumar. I’d greatly appreciate it if you could elaborate in class.