I just saw it again last night and all I could hear was "it's OK", from Jack, and the grunts and groans. In the book, Jack mumbles, "Guns going off"
You know Jack wears his heart on his sleeve, but Ennis keeps his deep inside him. Alma and no one else can get to his heart, except Jack. Jack knows the direct route to bring Ennis quivering to his knees in a flash. I think it hurts Jack when he does it but he can't help it. When Ennis is in emotional pain is the only time that Jack knows how Ennis feels.
Jim