To make a success from this play, Henrik Ibsen needs to set his characters up in various stereotypes. Nora is the typical housewife; frivolous and with no responsibilites outside the care of her children - just the way it's supposed to be. Norway, as most European countries of the day, defined the male and female roles distinctly.
When a woman marries she becomes her husband's possession and must behave appropriately. She is Torvald's "singing lark" and "little spendthrift" which reveals the extent to which Nora must ( or so they both think) rely on her husband.
Torvald typifies this behavior, which will ultimately be his undoing. He believes he is the perfect husband. By using nicknames, Torvald basically keeps Nora in her place. He gives her money - although not without a show - he showers her with affection - albeit shallow and he ensures she gets to do the things women are "expected" to do. His ignorance of the real goings on inside his own household reveal his complete dependence on roles and expectations. Nora's character is thus sealed by Torvald's rules and regulations to which she submits.