How do you know dally felt atleast partially responsible for johnny's fate?

Dally felt at least partially responsible for Johnny's fate because he expressed deep sorrow and guilt after Johnny's death in "The Outsiders." He had tried to protect Johnny and was deeply affected by his injuries, indicating that he believed he could have done more to save him. Furthermore, Dally's emotional breakdown and subsequent reckless behavior suggest he was grappling with the weight of that responsibility, ultimately leading him to seek a way out of his pain.