How we cite our quotes:
I knew it. In this way, Peeta's not hard to predict. While I was wallowing around on the floor of that cellar, thinking only of myself, he was here, thinking only of me. Shame isn't a strong enough word for what I feel. (13.21)
Peeta's loyalty to Katniss is unwavering. When the news comes that they have to go back to the arena, Peeta instantly starts "thinking only of [Katniss]," springing into action on her behalf. In a way, this seems almost too selfless. Katniss, for her part, has a pretty normal reaction: freaking out on her own behalf. Most of us would probably do the same thing.
And the more I come to know these people, the worse it is. Because, on the whole, I don't hate them. And some I like. And a lot of them are so damaged that my natural instinct would be to protect them. But all of them must die if I'm to save Peeta. (16.85)
The Games take so much away from those who compete in them, even down to their ability to be loyal to more than one person. According to the design of the Games, ultimately each person can only truly be loyal to him- or herself. Even here, Katniss is stretching the rules by deciding that her ultimate loyalty is to Peeta rather than herself. When it comes down to the two of them, will she be able to stick to that?
It's stupid, I know, that his efforts make me so vexed. All I wanted was to keep Peeta alive, and I couldn't and Finnick could, and I should be nothing but grateful. And I am. But I am also furious because it means that I will never stop owing Finnick Odair. Ever. So how can I kill him in his sleep? (20.13)
In a way, Finnick has outsmarted Katniss here by saving Peeta's life. Now Katniss "will never stop owing Finnick." He's done her the kind of favor she can't easily pay back; now she can't let him down. Inside the arena, this kind of relationship will ultimately be a liability – nobody wants to have to kill her own friends.