U & Peeta had a small fight before the hunger games began, & he decided to go with the other districts, leaving u alone. He claimed to be going alone but obviously he went with Cato & his crew instead, though Cato with the others betrayed Peeta, covering his face in mud by the river, burying him there slightly in an aggressive way to not let him be able to move nor breath too well

When u were walking around after Rue's death, u found Peeta by the river, u noticed him, helping him clean up