No one person can take responsibility for Andy's death. No one person could have saved him either. It is a combination of things that lead Andy to his ultimate choice.
Parents: The parents just want to get the horrible experience of Robbie's death behind them. They want Andy to move on with his life. They dump the whole issue into the hands of the psychologist, believing that since they are sending him to a professional, it will all be OK. The professional will "fix" him. When Andy tries to talk with his mother, she suddenly has a headache. Andy says,
"She doesn't understand that this time there is no one to pull me out...I'm drowning again, only this time, Mom, I'm in an ocean." (pg 140)
Psychologist: Andy is able to fool the psychologist into thinking that he is OK. He takes Andy's word for it that he is fine with his grades, his schooling, and his relationship with Keisha. Andy does try to call him before he kills himself, but he isn't there, due to a real tragedy in his own life. However, he should have had a better idea of what was going on with Andy and not dismissed him from treatment.
Friends: His friends try to help. When someone talks about death and depression all the time, it gets old. They went to the counselor, the counselor passed it off to the psychologist and told the boys not to worry about it. They tell Mrs. Thorne,
"Andy only seems happy when he's with Keisha or when he's actin' weird. And we didn't know who else to talk to"
Coach, counselor, and the teachers: There are some teachers who are seriously concerned about Andy. The coach is one and the English teacher is another,but they have limited contact with Andy. They see Andy in the school setting, and he is missing a lot of class. Andy isn't truthful with them either. He tells the coach when the coach informs him of the college scouts who came to see him,
"I know I'll get another chance. You wait and see. Scouts from all over will be here to check me out." ( pg 144)
What he really felt was
"When they see my low grades, all my absences, and my police record, they'll break their necks runnin' away." (pg 145)
Andy himself: Andy does not want help. He lies to the psychologist, he lies to the coach, he lies to his parents, he alienates his friends. They can only work with what he gives them. His friends are very angry with him at the end of the book because they feel that he had a choice, and he didn't try.
Gerald says, "You are a coward and a sellout!" (pg 173)
Tyrone says, "Robbie's death was an accident. Somehow I can deal with that, but what you did, it just don't make no sense to me." (pg 172)
Keisha says, "Nobody understands why you decided to end your life when you had so much to live for. So you're out of it and we have to stay here, feeling your pain as well as our own. It really isn't fair, you know." (pg 178)