Reiha McLelland would be alive today if it were not for her "inappropriate" relationship with her intermediate school teacher, the teenager's psychiatrist has told the inquest into her death.
But he also conceded there were errors in his treatment of the 13-year-old which he said could have made the difference between life and death.
The inquest into the death of Reiha MClelland has also heard she was the focus of "grooming" by her former teacher Sam Back, 42, in the time leading up to her death in August 2014.
The hearing is being carried out at the Wairoa District Court after the power cut in Gisborne disrupted the week's hearing planned to be held there.
Reiha took her life in 2014 after a police investigation and an inquiry by the Education Council NZ into her involvement with Back and his partner Angie Mepham, also a teacher.
The psychiatrist, who has name suppression, has testified that Reiha was "in love" with Back and the end of the relationship was as if she was going through a "divorce".
At the inquest the family's lawyer Moira Macnab asked the psychiatrist: "But for Mr Back, do you think Reiha would be here now?"
The psychiatrist responded: "My personal view is yes. She was traumatised by the relationship in an irrevocable way."
There was evidence that Reiha - who had refused to speak of her relationship with the teachers - had said she was concerned "Mr Back might go to jail".
The psychiatrist said he was concerned about the relationship.
"I had already been concerned about Mr Back grooming Reiha by entering a relationship with her, becoming increasingly intimate and not respecting boundaries which were gradually eroded by ... keeping it secret."
Evidence has been produced during the hearing that Reiha and Back exchanged about 4000 text messages. Today, it emerged some of those messages were repeated texts from Back when he hadn't had a response from the teen.
Further concerns included the sighting by a health worker of the pair holding hands as Back lay on Reiha's hospital bed during an admission. It was this which sparked a police investigation that did not lead to charges being laid.
Back's lawyer Adam Simperingham asked the psychiatrist if there had been any evidence of a sexual relationship.
The psychiatrist said there was no evidence of sexual contact. He also said he was aware after Reiha's death of an entry in her diary in which she wrote: "He's never touched me inappropriately."
Questions from Simperingham focused on the psychiatrist's admission he made a mistake by not explicitly warning her parents the teen had sought out, obtained and then returned the means by which she eventually took her life.
The knowledge of this was a disclosure made by Reiha to her mental health worker and one which had been raised with the psychiatrist.
Instead of telling her parents or police, the mental health experts had accepted Reiha's assurances she no longer wanted to take her life and no longer had access to the means. The decision was made to help build trust with the teenager, he said.
Simperingham asked the psychiatrist: "But for your decision, would Reiha be here today?"
He replied: "I think it's quite possible she would be and that's what I have to live with.
"I accept it was a mistake not to tell them. At the time, I minimised the enormity of the weight Reiha was carrying."
He said he did so not knowing the degree of the relationship with Back - a claim challenged by Simperingham who asked what more he needed to know.
"You assumed the worst of the relationship. You assumed it was a sexual relationship," he asked.
The psychiatrist responded: "Yes."
Simperingham raised question over the psychiatrist's finding that Reiha was not mentally unwell or her behaviour abnormal.
But the psychiatrist responded:"'I don't think there was anything abnormal about Reiha in the context of the situation she was in. I think she was doing the best she could in a very difficult situation.
"[She was] having an intense, emotional relationship with someone  years her senior who was a former teacher asking her for help and support for himself and - this is presumptive - to keep this secret from everyone."
Reiha's relationship with her mother was also questioned with Simperingham pointing to the teen's diary entries which included one in which the teen said she "hated" her mother and "as soon as I'm 18 I'm moving out of this s**t hole".
The psychiatrist said he didn't consider that - or similar entries - suggested a poor relationship and suggested it would be familiar to any in court from their teenage years.
Psychiatrist Dr James Cavney, called by Back's lawyer, said he did not consider Reiha was "in love" from the text messages. Instead, he said it appeared Reiha had idealised Back and Mepham as parental figures.
"There's wasn't a sexual element I could see. So what else was she seeking?"
Reiha was in Back's Gisborne Intermediate class during 2013, during which time contact outside school began to take place. The contact included emails, text messages and sleepovers at his house during times when his partner was and wasn't present.
Both Back and Mepham have been before the New Zealand Teachers Disciplinary Tribunal following a complaint by Reiha's parents. Back was struck off and Mepham was cautioned but allowed to continue teaching.