In Act II we see that her ambitions lead to a mysterious surprise in which she borrowed money from Krogstad, a man who worked for Torvald, so she could travel with her husband and family to Italy because of her husband's illness. She lies to Torvald that her father gave them the money, but the problem was that this happened after her father's death. This is where the drama starts and Nora starts to stress out on how she is going to pay the debt; and on top of that, Torvald is firing Krogstad and giving his position to Nora's friend, Kristine Linde.
Nora is very immature and Linde tells her to grow up because Nora thinks that everything is money and that money means happiness. At first, the author has us thinking that the characters of Nora and Linde are very different; Nora being so ambitious and wanting money for her desires and Linde struggling to get money to take care of her siblings and mother; but later, we learn that they are not so different after all. Nora hides the secret of borrowing money from Krogstad to help her husband and is now stressing out to pay the debt.
I think that Nora should tell Torvald about what she did because sooner or later he will find out and everything will turn into a mess. If Krogstad sends the letter to Torvald saying what Nora did, Torvald will get mad, so that is why I think that Nora should tell him before Krogstad, even though if she thinks that he will be embarrassed.
This play certainly shows how male and female genders are not equally treated. First of, because of how Torvald treated Nora, calling her different nicknames and always treating her like a little girl, like if she was not capable of doing anything important; he thought her only job was to be in the house, cleaning it and taking care of her children. Secondly, because Nora was afraid of telling Torvald that she borrowed money from Krogstad and that she was going to pay him back, making him seem like he was not capable of paying his own things and having his wife paying them for him.
In Act III, we see that everything is revealed and Torvald finally knows what Nora did. Instead of being thankful, he gets mad at her and is embarrassed of Nora borrowing money from Krogstad for his own illness. At the end, Nora decides to leave the house and maintain herself, without Torvald's help. This is where her character changes and goes out looking for a new start and new life. It was very unexpected to see that Nora will leave Torvald and would face him like she did, which I think it was the start of Nora becoming more mature and able to make her own decisions.