She was leaving him.
It was dinner time and they had no food to eat.
All their rations freely given to them by their employer, farming husband and wife, John and Sarah Mawbey, had been exhausted.
This was because Jimmy had invited some male relatives and a friend to stay with him, and they had eaten some two-thirds of the rations meant for two adults and a small child.
Jimmy had not only used up all the rations, he was 15 shillings in debt for those he had been given generously in advance by the Mawbeys.
Ethel was fed up with living in a humpy by a creek, an isolated existence with no family or friends for support.
After she had married Jimmy in December 1898, she had moved into his father's house next door to that of her parents at Wyaldra Creek on the outskirts of Gulgong.
She had apparently not anticipated having to 'camp out' with her husband, even though she knew he was an itinerant farm worker.
Most of all she was fed up with Jimmy's refusal to stand up to the Mawbey women and the female school teacher about their salacious and malicious comments about her sexual relationship with a black man.
She wanted him to defend her honour, to teach them some respect.
There were several valid reasons Jimmy had found this hard to do.
Ethel had decided she wanted a better life.
She was starting to put on airs and graces, even using the same expressions as the school teacher with German parents, like 'pooh' to dismiss what he said to her.
And Mrs Mawbey had advised her that if she wanted a better life for herself and her 15-month-old son, she would have to leave Jimmy.
Jimmy later told of the heated discussion he had with Ethel at their camp that evening, before the two of them left to murder the Mawbeys.
My wife and I had a word or two about cooking and something or another about the camp.
With that I said, 'I suppose I am in this world alone with no one to care for me. I thought you was my wife.'
She said, 'Go to the devil.'
Everything I said to her she said, 'Pooh, that's nothing! Pooh, that's nothing!'
With that me and Underwood cleared out.
I thought I might as well die, so the Mawbey murders were committed.
A couple of days earlier, Jimmy had broken all the crockery in the camp because he was planning to leave.
This meant there would be nothing heavy to carry by people travelling on foot.
But it could also have symbolised the breakdown of Jimmy and Ethel's domestic arrangements, the end of their marriage.