Tribunal documents state the man formed an "inappropriate relationship" with a 13-year-old pupil, who the hearing heard has since died.
Her death is before the coroner.
In 2013 and 14, the male teacher allegedly "engaged in prolific text messaging and emailing" with the girl, communications that became "increasingly intimate and intense".
The girl stayed at the teacher's house five times, three times when his partner was home and twice when she was away.
The male teacher is also accused of giving the girl gifts and when she was in hospital at one point, was seen cuddling the girl and holding her hand.
He is also accused of failing to report worrying incidents to do with her mental health, including her cutting herself and asking him to "save me".
The female teacher's alleged serious misconduct relates to those events.
The girl's mother gave evidence to the tribunal, saying she noticed a change in her once popular, outgoing and sporty daughter.
After the mother became aware of the relationship, she said her daughter was reluctant to talk about it and get the male teacher in trouble.
"From our perspective as parents it showed a relationship that was inappropriate... This all came as a complete shock to us," the girl's mother said.
"We consider [the male teacher's] behaviour went well beyond what we would expect as parents in a teacher, student relationship. He was dishonest and lied to us."
Psychiatrist Dr Craig Immelman worked with the girl and said she appeared frightened and like she was trying to hide something.
Both teachers argued their names should remain secret and the tribunal granted them interim name suppression, a decision that will be reviewed later.
The girl's family thought the matter should be in the public arena, council lawyer Dale La Hood said.
The hearing continues.