He is accused of engaging in prolific text and email conversations with the girl, whose death is now with the coroner.
It's alleged she slept over at his house, he gave her gifts and held her hand and cuddled her when she was in hospital in a relationship that began when the girl was in the man's class.
The male teacher is accused of allowing the girl to become emotionally dependent on him and impeding medical professionals trying to help her.
His partner, also a teacher, is charged with serious misconduct, over her knowledge of what went on.
The man today offered an apology to the girl's family.
"I know that saying sorry isn't enough. I tried my best to keep [the girl] safe and to convince her to re-connect with you so you can work it all out together because that's what family is about. I never ever spoke disrespectfully and disparagingly about you to [the girl]," he said to members of the girl's family, some of whom are at the hearing.
"In hindsight I can say that I lost my way and became too involved in a student's life."
To his partner, who he said was so sick with a gastric illness at the time he thought she might die, the man tearfully apologised for "dragging you into this".
"I don't know how I'm going to make it up to you but I plan to."
The male teacher said he was popular among pupils and had built a strong reputation over his decade in the profession.
"You can talk to my principal and he'll tell you I'm very respected by members of the community."
His too-close relations with the girl began one night when she arrived at his house during a storm, having run away from home. He later let her stay over when she was looking for a safe place.
He found out the girl was self-harming, which he mentioned to a colleague.
As the situation developed, the girl said she would run away if the male teacher told anyone about her struggles and he became stressed.
The girl spoke of problems at home but was not specific, the male teacher said.
Now he realised he was in the wrong.
"I was too close to the situation to make more appropriate professional decisions," the man said.
"[The girl] would often say to me this is a weird friendship eh? I would respond, saying we're not supposed to be friends. 'I'm your teacher'. She would say, 'nah, it's OK, you're a great friend and a great teacher'."
The girl later told the police officer about the man: "He listens, he understand me."
The police cleared the male teacher of any criminal wrongdoing, as the investigating officer wrote: "I genuinely believe he had [the girl's] best interest at heart... It's easy to see how he got sucked into a situation he had very little chance of controlling."
The teachers' lawyer Janette Andrews said the male teacher admitted crossing professional boundaries but denied adversely affecting the girl's emotional well-being.
A report from a psychiatrist that said the girl's refusal to talk openly about her relationship with the male teacher impeded her treatment was "self-serving".
The male teacher admits the serious misconduct charge but disputes some of the allegations against him. His partner admits wrongdoing but says it doesn't amount to serious misconduct.
The names of the teachers, the girl, the schools involved and where this happened are suppressed.
The hearing continues.
