Nora and Torvald are not equals in the relationship. They are not a couple working together, but a...
Let's begin with Nora and Torvald. Here is what we witness throughout the play, which is backed by the fact that their relationship is over by the end of the play.
Nora and Torvald are not equals in the relationship. They are not a couple working together, but a couple where the man overpowers the woman.
On top of the lack of equity, there is also a lack of fairness in treatment. Torvald uses Nora as his wife, as the mother of his children, as an entertainer, and as his personal "doll" of sorts. He is patronizing and, in many occasions, condescending. In turn, Nora puts Torvald on a pedestal and would never be disrespectful to him.
There is nothing honest about Torvald and Nora's marriage. She acts for him, hides situations from him, goes behind his back even to eat a macaroon, and basically has to live a parallel life that meets his needs—rather than her real life.
Did you notice how cruel Torvald turned toward Nora when he saw that his ego, his reputation was potentially put at risk due to Nora's secret? The words that Torvald said to Nora seemed to come from a place where they have been brewing. It seems like Torvald had those words reserved for when the situation merited it. The cruel words he used were in no way justified. It symbolizes how much control Torvald had over Nora. He could make her or break her on the spot.
In contrast, Krogstad and Kristine Linde show a drastically different side of how relationships can work.
There is equality in their relationship. Both parties admit their wrongdoings in life. Both parents admit to be "shipwrecks." Both parties admit to be vulnerable and in need of help. Both parties agree to complement each other and helping each other out. Krogstad and Kristine treat each other fairly, taking into consideration their strengths and weaknesses.
There are no secrets between Linde and Krogstad. If anything, they are entirely open about their pasts and their present, which is why they have a chance at a future together.
Further, there is zero cruelty in Kristine and Krogstad's relationship. The man does not try to overpower the woman with insults or hurtful statements. Linde is really straightforward with Krogstad, and vice versa.
It is ironic that the picture-perfect Helmers, who have every resource available to make each other happy, are the easiest to break apart, whereas the two "shipwrecks" who lack money, jobs, status, and class distinctions found one another and are ready to become a strong couple.