I do think that Plath was able to detail conditions of characterization that are realistic. She is able to detail the challenges of being a woman in a setting where identity was defined in a narrow and constrictive manner. Plath was also able to construct a social setting in which mental illness was not fully understood.
For Plath, the ability to fully grasp these dynamics are what help to make her characters realistic and approachable. Esther finds that her identity is challenged by social elements such as gender and class. It is for this reason that she has such a challenging relationship in viewing other women in the novel. The women the novel that Esther encounters suffer from this same condition in which social expectation helps to cause a challenge with internal notions of self. Whether they are seen as friends, women mentors, or competitors is reflective of a social setting that does not authenticate or fully validate her voice. This was a realistic condition of the time period for many women and is one that enables her character to be seen as realistic. In addition to this, the complex relationship that Esther has towards her mother is what further makes her realistic. Esther has distinct feelings towards her mother, reflective of a real condition in which people struggle throughout their adult lives to make sense of some of the most basic relationships.