he is under a spell he cant help it
Katniss and Peeta were going to break off the alliance the night the careers came to get them
The alliance the the hunger games book# 1 is peeta and the Careers (districts 1,2, and 4) andPeeta and Katniss towards the end The alliance in catching fire book #2 is peeta Katniss finnick Johanna wiress and beetee
The Careers call Peeta "Lover Boy".
At the beginning of the games, Peeta joins the careers because he thinks it gives him a better chance at winning. He does quite well until the careers either see though him or finds out his plan, and injures him, leaving him for dead. Then Katniss finds him.
The Careers use Peeta to figure out what Katniss' skill was that got her the eleven from the Gamekeepers. The Careers also think that Peeta might know Katniss' whereabouts.
The Careers, if you have not read the book, I really suggest it! It is violent and awesome!
While in the Games, Peeta appears to align with the Careers.
That Peeta has teamed up with the Careers and is helping them find her and kill her.
The careers
Because he joined the Careers, or the the tributes from the first 3 districts which form a temporary alliance and prey on the weaker contestants. But the only reason why Peeta joined them was so that he could protect Katniss from them. In other words, he was acting as a double-agent
Well, a District 3 boy is seen guarding the camp in the scene where Katniss shoots the apples, but Peeta Mellark is the first tribute from a different district to be allowed into the Career pack. It is later revealed that Peeta never trusted or liked the Career tributes, and clearly only joined the Careers to stay alive.
At the end of Mockingjay, Katniss chooses Peeta.