He joined the careers? How could he! What about all he on the roof before the game, was it all a lie?
In Katniss' flash back about how she meet Peeta and now Katniss is having a hard time debating on whether she should kill Peeta or let someone else do it. Katniss is conflicted about her feeling Peeta helped her during a hard time in her life and she feels she must repay him.
When Peeta announces his love for Katniss, Katniss is has more conflicting feelings. Later we find that this whole confession was planed by Peeta and Haymich to get more sponsors. This is important because tributes need sponsors to win the games. Sponsors can give them gifts to make it easier to survive.
Once Katniss knows that Peeta had joined the careers she is conflicted and mad at Peeta. It hinders her thinking and poses a threat to her survival.
During rues death, Katniss put flowers on Rue's dead body this is important because the Gamemakers considered this a rebellion. For the reason that in the games the tributes are supposed to kill for no remorse for entertainment for the capitol. rues death could also be a step or lead to a rebellion.
Once it was announced that there can be two winners if their from the same district, Katniss goes out to search for Peeta. During this time Peeta is hurt and Katniss stays to help him even though it was dangerous. couldve killed him to win by herslf she didnt could mean she likes peeta.
Once the Gamemakers revoked the first rule change Katniss thought of a plan to trick the Gamemakers to allowing both her and Peeta to win. The plan worked and now both Katniss and Peeta worked, but now Katniss could be in danger. the plan was considered a big sign of rebellion to the Gamermakers and now they are mad. This could pose a dangerous future for Katniss.