IN the days before a Sydney restaurateur fatally stabbed her husband in the chest, the pair had argued about whether she was having an affair with a personal trainer and whether she had cooked him abalone soup.

But yesterday a jury rejected the Crown case that a “fed-up” Qian Liu had intentionally stabbed her husband with a small kitchen knife during a confrontation inside their Riverwood granny flat late on the night of January 3, 2016.

It took the jury just 90 minutes to find Ms Liu not guilty of the murder and the manslaughter of her husband Han Lim Chin, 39, following her murder trial in the NSW Supreme Court.

The presiding judge, Justice Clifton Hoeben, smiled and said it was the first time a jury had delivered a “not guilty” verdict in his 13 years of trials.

Moments later a beaming Ms Liu walked out of the King St courthouse a free woman.

During the trial Ms Liu’s defence barrister Phillip Boulten SC argued the 35-year-old never meant to harm her husband and that she had reacted to a “nasty situation” when an aggressive Mr Chin confronted her, holding a ceramic knife behind his back.

“What happened was a terrible, tragic accident and it occurred when she was trying to make sure her husband could not regain control of the knife,” Mr Boulten said.

He said his client was unaware the protective cover of the knife she was holding had slipped off and described her actions as a “spontaneous reflex reaction”.

He said Mr Chin had been aggressive and had two knives in a bum bag he was wearing.

“What she did when the wound was inflicted she did not do deliberately,” he said.

Crown prosecutor Brad Hughes SC argued Ms Liu had deliberately inflicted a “penetrating wound” to either cause her husband serious harm or kill him.

Throughout the trial the jury also heard how Mr Chin had asked his wife to send sex tapes of themselves to her personal trainer so he would “give up”.

A police officer also gave evidence at the trial and recalled Ms Liu saying to him: “I stabbed him, we argued and I was mad”.

Ms Liu denied saying these words when she gave evidence and also denied having an inappropriate relationship with her personal trainer, who worked at Fitness First.

After her arrest she told police in an interview: “Out of no proof, no reason, and he suspected me that I had someone else outside of marriage.”

Ms Liu said the pair started dating in 2008 and married in 2012.

After her wounded husband collapsed on the night of the incident he said, “Wife do believe me, I do love you very much”.