How is their guide, Mr. Kapasi, characterized? (Jhumpa Lahiri's “Interpreter of Maladies”)

Mr. Kapasi is a romantic who empathizes with the pain of others. While these characteristics are useful in his job as a medical translator, the “interpreter of maladies” of the title, they also sometimes block him from accepting life’s practical realities. One of those realities is that his earnings as a translator are inadequate so he must supplement them, which he does through working as a tour guide.
In the second job, Kapasi’s empathy is less advantageous. Imagining himself having the tourists’ lives, he romanticizes them and sometimes places himself as a subject within their very different reality. Kapasi will probably never have disposable income to travel the world. When he envisions himself in a relationship with Mrs. Das, he soon learns that her life back home is far from idyllic. Although she enjoys material comforts, her romantic yearnings—in that case, acted upon through an affair—have not been significantly fulfilled much more than his own, unstated desires. Through this interaction, he has perhaps progressed as an interpreter of his own maladies.

Mr. Kapasi, the tour guide hired by the Das family, is characterized as a fantasist, saddened by the difficulties of his personal life and seeing escape in his imagination. The emotional life of Mr. Kapasi is vivid and strong, so when he begins to develop romantic feelings towards Mrs. Das, a superficially attractive woman, his disappointment upon realizing that she is not worthy of his fantasy is intense.
When he is not leading tours, Mr. Kapasi is an interpreter at a doctor's office, so he often finds himself speaking of physical complaints, pain, and other problems that afflict the sick and elderly. Though this role gives Mr. Kapasi opportunities to develop and practice empathy, it also gives him a lot of exposure to sadness. This exposure as well as his own loveless marriage and the death of his young son makes Mr. Kapasi a disappointed person, so when he realizes that Mrs. Das is not at all the woman he thought she was, he feels the shock more strongly than seems suitable.