The characters in Long Day's Journey are absolutely obsessed with thinking over the past and either feeling guilty about what they've done, or blaming someone else for all the problems they face. Once one of the children dies at a young age and the mother becomes addicted to morphine, everyone keeps worrying about whether they should have had another kid, who was responsible for the baby's death, why the mother became addicted to morphine, and generally how they or others have failed as good mothers, fathers, sons, and brothers.
James is basically incapable of subordinating his own obsessions to the desires of others. He makes a show of sentimentality and compassion, but in the end he can't look far beyond Numero Uno.
James's and Jamie's thinking is dominated by a causal logic that always includes blame. No action can occur that isn't someone's fault.