NORA: "Tell me, is it really true that you did not love your husband? Why did you marry him?" MRS. LINDE: "My mother was alive then, and was bedridden and helpless, and I had to provide for my two younger brothers; so I did not think I was justified in refusing his offer." (1.136-1.137)
Christine was forced to give up on love in order to save her family.
NORA: "Nonsense! Trying to frighten me like that!—I am not so silly as he thinks. […] And yet—? No, it's impossible! I did it for love's sake." (1.413)
Nora is under the impression that love supersedes the law.
NORA: "Yes, a wonderful thing!—But it is so terrible, Christine; it mustn't happen, not for all the world." (2.322)
Nora thinks the wonderful thing will be when Torvald sacrifices himself for her, proving his love. She's also terrified of this because it will destroy him. In the end, Torvald just doesn't love her enough to sacrifice himself.
NORA: "You know how devotedly, how inexpressibly deeply Torvald loves me; he would never for a moment hesitate to give his life for me." (2.189)
When Torvald fails to do this at the end of the play, it proves to her that he just doesn't love her as she thinks he should.
RANK: "You [Nora] can command me, body and soul." (2.202)
Is Rank in love with the real Nora, or the idea of her?
HELMER: "Now you have destroyed all my happiness. You have ruined all my future." (3.238)
After Torvald finds out the truth, all he seems to be worried about is himself. Does this mean he never really loved Nora?
HELMER: "Empty. She is gone. (A hope flashes across his mind.) The most wonderful thing of all—?" (3.381)
Has Torvald come to understand what real love is in this last moment, or is it something else entirely?
HELMER: "Do you know, when I am out at a party with you like this, why I speak so little to you […] It is because I make believe to myself that we are secretly in love." (3.139)
It's telling that Torvald's fantasies relegate his feelings for Nora to secret infatuation.
Mrs. Christine Linde
MRS. LINDE: "Two on the same piece of wreckage would stand a better chance than each on their own." (3.44)
Christine's offer of love is strikingly different from the Helmers' discussion of their affection. Rather than being some idealized version, it's tempered with harsh reality.