Nora is a tragic victim primarily because she is the "doll" wife to Torvald. She has no real identity of her own and is never taken seriously by her husband. She is simply this "porcelain doll" that acts on command and is there for everyone to admire her beauty. This is an illustration of the reality of 19th century Europe, where a wife was regarded as property and not as an equal partner. To make things worse for Nora, she is forced to lie to Torvald because she is trying to be this perfect "little" wife he desires. He not only treats her as his prized possession (similarly to owning his home and other valuable possessions), he further humiliates her by treating her like a child. He "lovingly" refers to her with pet names such as "singing skylark," "little squirrel," and "little spendthrift," while patting her on the head like she is his daughter instead of his wife. As a result, Nora believes she is totally dependent upon her husband to survive, that is of course, until the end of the play.
This reason this Nora is a tragic victim is because she is a product of the time period and the social attitudes that repressed her true desires loving her husband as an equal. It is not until she realizes his "fakeness" and deceit that she has the power to take control of her life and leave her husband. Most readers sympathize with Nora and are routing for her to get a backbone, as she does when she leaves Torvald in the end of the play.