I think that it is part of Tagore's genius to make the complexity in the relationship between Ratan and the postmaster so much a part of the text.  Both of them bring complex baggage into the relationship, only adding to the complexity of their interaction.  The postmaster has been thrown into Ulapur from Calcutta. He is completely cut adrift in Ulapur, wishing only to be placed back in the metropolitan center.  He is alienated from all others and cannot find any reason to remain there.  Ratan is an orphan, cut adrift in her own way, seeking to find some type of center.  Both of their dissatisfaction with their own condition in life cause both to find a certain type of sanctuary in one another.  For the Postmaster, the companionship he enjoys with Ratan is one in which there is definitely a feeling of inclusion that both experience.   As the inclusion becomes more pronounced over time, the bond between them strengthens.  Eventually “Ratan referred to the postmaster’s family his mother, sister, and brother- as if they were her own… forming affectionate pictures of them in her own mind.”  Tagore develops this even more, adding to the complexity.  When he takes ill, she began to "soothe his illness and loneliness with feminine tenderness.”  It is here where Tagore makes it evident that there is something beyond mere friendship with both of them.  Yet, he does not say there is a relationship.  It is this ambiguity and complexity that makes the ending brutal for Ratan.  Tagore's own narrative at the end in which he argues that emotional pain is one of the few constants in the modern setting is where there is even more complexity generated.  For Tagore, as demonstrated through the relationship shared between Ratan and the postmaster, there seems to be a small degree of variance between the emotional nuances of closeness and separation.  In this, there is complexity, something that he brings out in the relationship between both characters.