The maths teacher and the 14-year-old student, who was in his class last year, began chatting on Instagram on February before beginning a relationship in June.
For her parents, the teacher is a sexual predator, despite their daughter's claim that the pair are in love.
"She's a child who believes in love with a capital L. As a teacher he knew that and used it to seduce my daughter," her mother told AFP.
The government has promised to change the law after a man was acquitted of rape earlier this month, as the jury found no evidence he had forced an 11-year-old girl into sex.
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Currently, sex with a minor aged under 15 is classified as sexual assault, punishable by up to five years in prison.
Adults wielding some form of authority over the child face stiffer sentences.
In a speech on sexism to mark the UN's International Day for the Elimination of Violence Against Women on Saturday President Emmanuel Macron said he wanted a minimum age of consent of 15.
In recent years there have been several trials in Western countries involving teachers who slept with students, the most famous being that of American woman Mary Kay Letourneau.
Letourneau was a 34-year-old married mother of four when she began a relationship with a 12-year-old student whom she later wed.
She served seven years in jail for unlawful sex with a minor.