Hester being too late in her self-reflection and realization
We could say that one of Hester's main traits is her self-centeredness. She is unapproachable and cold which leads to her life of loneliness. Her obsession with Katherine could also be seen from perspective of her self-centeredness. What Hester fails to do is self-reflect on time, before it's too late. She doesn't realize that she is holding Katherine back, holding her prisoner in a sense, until the young girl appears to completely lose her mind and start obsessing over the man in the well. Hester is too late in her realization of the love Hilde has given her, thinking of young Hester even when her world is falling apart. Mr. Bird is also one of the people Hester is too late to thank for the unconditional care. Overall, Hester is too concerned with herself that she can't see past the end of her nose.
Hester's selfishness in her selflessness
There is obvious selfishness in Hester's selfless act of taking Katherine under her wing and taking care of her. Katherine is there to fill the emptiness of her loneliness. It could be said that Hester needs Katherine as much as Katherine needs her, if not more. Katherine seems rather like a doll, a tool that Hester uses against her own loneliness than another human that she cares for. This could be seen from examples when Hester begins to doubt that Katherine stole her money or when she forces Katherine to retrieve the money from the body of the man from the well by threatening and reminding her who it was who killed him.