Nora, chafing at constantly being underestimated, ends up confiding in Mrs. Linde near the start of Act 1, seemingly wanting to discreetly unburden herself by sharing her secret about the loan. In an act of situational irony, though, Nora’s attempt to ease some of her worries and frustrations ultimately exacerbates her circumstances later in the play:
Nora: You’re just like the rest of them. You all think I’m useless when it comes to anything really serious…
Mrs. Linde: Come, come…
Nora: You think I’ve never had anything much to contend with in this hard world.
Mrs. Linde: Nora dear, you’ve only just been telling me all the things you've had to put up with.
Nora: Pooh! They were just trivialities! [Softly.] I haven’t told you about the really big thing. [...] Nobody must know about it, Kristine, nobody but you.
Telling Mrs. Linde this secret turns out to backfire on Nora spectacularly, ironically leading to even more troubles and the eventual dissolution of her marriage. Following Nora’s confession, Mrs. Linde condemns the fact that Nora has introduced deception into her marriage, and it is Mrs. Linde’s very dedication to truthfulness that ultimately cements the chain of events that lead to Torvald’s discovery of Nora’s deception. Nora’s attempt to unburden herself from the stress of keeping her family afloat thus ends up leading to even more trouble and hardship.
Dr. Rank’s enjoyment and indulgence of all things unhealthy and decadent following the diagnosis of his terminal illness is an example of situational irony, especially considering that he traces his spinal tuberculosis to his father’s own possession of these habits:
Torvald.: You seemed to be having a pretty good time upstairs yourself.
Rank: Capital! Why shouldn’t I? Why not make the most of things in this world? At least as much as one can, and for as long as one can. The wine was excellent [...] Well, why shouldn’t a man allow himself a jolly evening after a day well spent?
The joy Dr. Rank takes in letting loose, eating and drinking to his heart’s content, is also tinged with irony because of the fact that he is only able to reach such a stage of enjoyment after finding out such bitter news. His desire to live to the fullest for whatever time he has left foreshadows Nora’s imminent decision to leave Torvald and enjoy her own life for as long as she can. By choosing to indulge in his desires, Dr. Rank sets an example for Nora to follow, demonstrating the fact that endings can also herald new beginnings.
As Nora and Torvald argue in the aftermath of the big reveal regarding her loan, Torvald asserts that no one could ever sacrifice their honor in the name of love, calling Nora a stupid child for thinking so in a perfect example of situational irony:
Nora: All the time Krogstad’s letter lay there, it never so much as crossed my mind that you would ever submit to that man’s conditions. I was absolutely convinced you would say to him: Tell the whole wide world if you like. [...] When that was done, I was absolutely convinced you would come forward and take everything on yourself, and say: I am the guilty one. [...]
Torvald: I would gladly toil day and night for you, Nora, enduring all manner of sorrow and distress. But nobody sacrifices his honor for the one he loves.
Nora: Hundreds and thousands of women have.
Torvald: Oh, you think and talk like a stupid child.
As the passage above demonstrates, although Nora is the one being insulted for her supposed childishness, Torvald is the one who is behaving like a petulant child. Exposed as a hypocrite and fickle man whose love is conditionally dependent on absolute doll-like obedience, Torvald scrambles to rescue his marriage from a situation of his own making (i.e. his bad reaction to the IOU letter). Nora’s revelation that she was planning suicide in order to protect Torvald makes his self-preservationist tendencies all the more disappointing and even pathetic in the face of her devotion, which he now finds himself forever excluded from.