"But you broke your vow, throwing it away with your life. And now you cannot say my name."
This was true. Hode moved his white lips, but could not say his brother's name. (2.10-11)
This is our first hint as to why suicide is so offensive on Gethen society. It's betrayal of those who love you. Keep the words "betrayal" and "love" in mind, here. They're going to be popping up a lot together as you read.
I was angry; for Ashe's love had always forced me to act against my heart. (6.9)
Notice how Estraven doesn't say "my love for Ashe." What's that tell you about the guy?
The furthest extreme from this practice is the custom of vowing kemmering (Karh. oskyommer), which is to all intents and purposes monogamous marriage. It has no legal status, but socially and ethically is an ancient and vigorous institution. (7.6)
Love and marriage, love and marriage, they go together like a horse and carriage—even on a planet without horses…or carriages.
What is love of one's country; is it hate of one's uncountry? Then it's not a good thing. Is it simply self-love? That's a good thing, but one mustn't make a virtue of it, or a profession…. (15.87)
Love, politics, duty: we're sure packing in a lot of themes here. But this quote does raise a good question: is love always borne out of hate for something else?
Maybe we have learned to pull together. (16.9)
This is the moment Ai and Estraven begin to fall for each other. From here on out, keep your eyes sharp for their ever-changing relationship.
We must compromise as to the heating of the tent. He would keep it hot, I cold, and either's comfort is the other's pneumonia. We strike a medium, and he shivers outside his bag, while I swelter in mine […]. (16.13)
Now that's love. Until you've had to share a sleeping space with someone who has a totally different internal temperature than you, you don't know what love is.
I was not paying my debt to him. Such debts remain owing. Estraven and I had simply arrived at the point where we shared whatever we had that was worth sharing. (18.22)
Compromise is the keystone to both love and survival on the Ice. Without it, you won't be going far in either.
I expect it will turn out that sexual intercourse is possible between Gethenian double-sexed and Hainishnorm one-sexed human beings, though such intercourse will inevitably be sterile. It remains to be proved; Estraven and I proved nothing except perhaps a rather subtler point. (18.23)
Ai and Estraven fall in love, but they keep the physical relationship separate. Okay, but does the same go for male/female relationships? Would we all really be better off without sex?
To those fisherman-villagers who live on the edge of the edge, on the extreme habitable limit of a barely habitable continent, honesty is as essential as food. They must play fair with one another; there's not enough to cheat with. (19.55)
Love, meet society. Estraven and Ai had to learn to share everything they had, but this whole community has been doing it since forever. Almost like it's not really that hard.
Even I betrayed him. I had said I would not bring the ship down till his banishment was ended, his name cleared. I could not throw away what he had died for, by insisting on the condition.
Love and betrayal, we welcome you back. For Ai to love Estraven, he must complete his mission. To do that, he must betray Estraven. It's complicated but it makes sense. In a complicated kind of way.