Quote 34
I don't know if it's the pods, or the fear, or watching Boggs die, but I feel the arena all around me. It's as if I've never left, really. Once again I'm battling not only for my own survival but for Peeta's as well. How satisfying, how entertaining it would be for Snow to have me kill him. To have Peeta's death on my conscience for whatever is left of my life. (21.14)
Throughout all the terrible things that Katniss and Peeta have endured, they've worked to protect each other. They've continually put their own lives at risk to save one another. Even now that Peeta's been hijacked it's no different. They've got too great a history together and been through too much together to desert each other now.
Quote 35
Why can't I just let him go? Slip him a pill, pull the trigger? Is it because I care too much about Peeta or too much about letting Snow win? Have I turned him into a piece in my private Games? (21.51)
Katniss can't define her feelings for Peeta, or rationally explain why she cannot "let him go." She just knows she can't. But the reasoning for why she can't is escaping her. We'd like to think it's because of her love for and long-standing friendship with Peeta, but here it also sounds it may be because he contributes to her plan for revenge.
Quote 36
They both laugh. It's so strange to hear them talking like this. Almost like friends. Which they're not. Never have been. Although they're not exactly enemies. (23.82)
Funny enough, the one thing that brings Peeta and Gale closer together is also what will always keep them apart: their shared love for Katniss. They both love her and don't know if she loves them back, or at least whom she loves the most. She's the one who holds the power – she's the center of their love triangle.