Then I remember. I can't protect Beetee, too. There can only be one victor and it has to be Peeta. I must accept this. I must make decisions based on his survival only. (25.10)
If there's ever a game to try hard to win, this is the one. But Katniss wants someone else to win: Peeta. She can't behave normally or even strategize to try to save the other players. As she understands it, she can only save one of them. To make matters worse, she has no way of knowing how Peeta will keep himself safe once she's out of the Games, so she has to stay alive as long as she can.