Mary Kay Letourneau and Vili Fualaau have permanently split after a failed attempt at reconciliation.

He was a 12-year-old boy in Year 6 and she was a 34-year-old school teacher when she first raped him 20 years ago. Through it all – puberty, a rape conviction, a prison sentence, 14 years of marriage and raising two children – they kept a relationship, despite Vili Fualaau filing for divorce from Mary Kay Letourneau in 2017.

The pair didn’t go through with the divorce and attempted to save their marriage, until now. PEOPLE has confirmed a legal filing with the King County Superior Court states that the couple is looking to finalise their split.

Letourneau, now 57, and Fualaau, now 35, had met in 1992 when the boy was in second grade at Shorewood Elementary School in the Seattle suburb of Burien, and entered an illegal sexual relationship four years later.

At the time, 34-year-old Letourneau was not only his teacher, but a married mother of four. Fualaau was less than two years older than her eldest son.

“The incident was a late night that didn’t stop with a kiss,” Letourneau told ABC in 2015, describing the first assault. “And I thought that it would, and it didn’t.”

The abuse went on in secret for months, before the teacher was arrested in March 1997, after her husband found letters about the affair. By then she was already pregnant with Fualaau's child. He was just 13.

Letourneau pleaded guilty to two counts of second-degree child rape, and was handed a suspended sentence of 89 months in November 1997. She served six months in county jail before being released on parole under the condition she attended counselling and didn’t contact Fualaau.

But within a matter of weeks of her release, she was found assaulting him in her car.

The parole violation saw her return to prison for the full 7.5-year sentence, where she gave birth to their second daughter behind bars on October 16, 1998. Both girls were placed into the custody of Fualaau's mother.

Less than a year after Letourneau was released from prison, the pair married in their home state of Washington.

A source close to the couple told PEOPLE they had a long history and a family but their relationship "really seems to have run its course."

"They worked really hard to fix things, but it still fell apart. The reconciliation just didn't work."