Realism is the literary technique that is used to describe each story element, i.e., setting, character traits, etc. without the use of elaborated imagery, or using literary elements such as metaphor or figurative language. The author will explain things exactly as they are without "sugar coating" or decorating the language, nor the attributes being described.
In A Doll's House, Ibsen uses mainly every secondary character to contrast dramatically with main character Nora. This is a clever and effective technique. While Nora spends her days glorifying her marriage, and lionizing her husband, there is a network of people who surround her that have to endure life for what it really is.
Mrs. Linde has lost a husband, is alone, has no money, needs a job, and has none of the wonderful opportunities that Nora claims to see waiting for her own self.
... now I am quite alone in the world—my life is so dreadfully empty and I feel so forsaken. There is not the least pleasure in working for one's self. Nils, give me someone and something to work for
Nils Krogstad has just lost his job lives his life bitterly over the loss of Linde and due to many other bad mistakes in his life. His blackmailing of Nora is nothing but his only attempt to take control of at least one aspect of his own life.
Dr. Rank is terminally-ill and explains so in a raw and somewhat nonchalant way. He is definitely angry at the fact that he is dying. Moreover, he is angrier at the fact that his illness was inherited by his father's excesses (presumably he has tuberculosis of the spine)
My poor innocent spine has to suffer for my father's youthful amusements.
Finally, Torvald, although is enjoying a major promotion at work, is obviously overworked and busy.
As it is evident, Nora lives in a fantasy world while the real world around her suffers, dies, works hard, and resents injustice. It is no wonder that, toward the end, Nora HAD to suffer some consequence from living in such oblivion. At some point, she had to grow up and join the ranks of the rest.
In Hedda Gabbler, Ibsen employs the same realistic techniques to define his eponymous main character as a vile predator, very much like the male character of Krogstad in A Doll's House. Hedda is also bitter. She wants to make others basically pain for her unhappiness and she even denotes a streak of psychopathy.
Oh courage… oh yes! If only one had that… Then life might be livable, in spite of everything.
Like Dr. Rank's father, Hedda's life choices have rendered her angry, unfulfilled, and bitter. She does not wish anyone else any joy, either. Her job is to twist their realities to the point to which they see life the same way that she does.
Similarly to Nora, Hedda refuses to grow up, accept consequences, nor change her status as "General Gabbler's daughter". Nora lives by the fact that she is "Torvald's wife". Yet, out of the two, Nora gets to achieve independence while Hedda aims to control everybody around her. Her psychopathy is even more evident when Lovborg commits suicide (another realistic situation) and she actually...admires him for it!
It’s a liberation [for me] to know that an act of spontaneous courage is yet possible in this world. An act that has something of unconditional beauty.
Therefore, the realistic storyteller does not aim to create a piece of aesthetic beauty. The aim is to expose life for what it could really be and to create characters who can be rendered weak by it.