When we examine the ending ofA Doll's Housewithin its context, we must accept the decision that Nora makes as the one and only choice available for her. Known as "The Father of Modern Drama", Henrik Ibsen purposely left this ending despite broad literary negative criticism because he purposely wanted to expose the real social problem that his character could have faced had she been a real woman. With this ending, Henrik accomplishes the modern twist that separates this play from all others of its own generation.
From a reader's perspective, one must explore how Nora has changed from the moment the play begins to that one moment that she is revealed the true nature of her marriage. Arguably, Nora's constant talking and her comments to Mrs. Linde seem to reveal a lot of her analytical thinking. When Nora speaks of her "deed" to save Torvald, and then contradicts herself over and over as to what his reaction would be if he finds out certainly show that Nora was way more ahead of herself than the reader thinks; she had already predicted and accepted that she had wasted her time in helping Torvald, and that his pride was much bigger than his love.
Hence, it is safe to conclude that Nora had already been preparing for this horrid moment where here dignity and pride would be crashed by her husband.
As a result of Torvald's actions, Nora's identity as a woman is shaken; Torvald insults the very foundation of her social duties by calling her a bad wife and mother.
Now you have destroyed all my happiness. You have ruined all my future!
She who was my joy and pride—a hypocrite, a liar—worse, worse—a criminal!
All your father's want of principle has come out in you. No religion, no morality, no sense of duty
Within her historical context, Helmer's insults to Nora would be no different than those of a modern day employer insulting an employee on her duties, only to try to "take it back" later. Hence, Nora must have weighed the value that she learned give herself as a woman against the value that her husband had just bestowed upon her; realizing that she values herself much more, she chooses to give herself a chance for self-discovery rather than to risk another chance at being misused and considered a second class citizen.
All things considered, poor Nora's identity and humanity were literally under-appreciated. In a situation of that kind, someone who wishes to preserve some degree of dignity simply leaves, even if it means to start over again.