Erin Patterson said she spent a "little fortune" to buy a "special meal" of beef Wellington for her beef beef steak and was disappointed that her estranged husband canceled her the night before lunch.

Simon Patterson began his evidence at Patterson’s murder trial, detailing their deterioration in their relationship about paying child support.

Patterson, 50, faces three counts of murder and one count of murder in connection with a beef lunch in Wellington, who served at her home in South Gippsland in 2023.

Patterson pleaded not guilty to murdering or attempting to murder his estranged husband.

She is accused of murdering Simon's parents Don and Gail Patterson, his aunt Heather Wilkinson, and attempting to murder Simon's uncle and Heather's husband Ian Wilkinson.

Simon started his evidence in the case of Patterson, answering the question “How do you know her?”

"I married her," he replied.

What follows is a deficit on the history of their relationship, from gathering with a group of "eclectic" friends who worked together at Monash City Council from the early 2000s to the mid-2000s to the drive through Nullarbor as a newly married couple.

Simon said shortly before their marriage in 2007, Erin's grandmother passed away, putting her property worth about $2 million. He said it was until 2015 that real estate executors slowly “shipped” her.

The couple has two children born in 2009 and 2014. But there are many separations in their relationship process, and finally reached the final form in the final separation in 2015.

Simon said the couple had been friendly, but until the dispute over child support was made in late 2022, his accountant unexpectedly filed a tax return that would “separate” him from Patterson.

He said it was the consequence of Patterson having to apply for child support, and child support authorities advised him to stop paying other expenses from his previous donations, including school and medical expenses.

After that, their relationship cooled down, Simon said, when their previous "talkable" text exchanges, including drama and political discussion, became clear.

They continue to share responsibility for their children and meet each other regularly, including the Korumburra Baptist Church where Ian Wilkinson served as pastor.

Simon said during a service held at the church on July 16, 2023, Erin invited him to lunch on July 29, 2023. She invited his parents and the Wilkinsons to spend the same service.

Simon agreed to go, but the night before lunch he texted her to cancel.

"I'm sorry for having lunch with you, mom, dad, dad, dad, Heather and Ian tomorrow, I feel so uncomfortable, but if you want to discuss it on the phone, I'm happy to talk about your health and the impact at another time," he wrote to the court at 6.54pm.

"Let me know."

Patterson then replied at 6:59 pm: “It’s really disappointing. I spent a lot of time preparing lunch this week or tomorrow because the problems I’m facing are exhausted and spending a small amount of money on the beef slices to make beef wellingtons because I hope it’s a special meal because I might not be able to hold such lunch again.

“It’s important for me that you’re all there tomorrow and I have the conversation I need to have.

"I hope you will change your mind. Your parents, Heather and Ian come at 12:30. I hope to see you there."

Simon said he did not respond. He has told his parents that he will not attend.

Simon became excited several times during the evidence, including detailing Don's views when he was visiting him in the hospital in the morning after lunch.

He said: "Yes, dad is much worse than mom, he's really struggling."

"Lying beside him, bent over. His face changed color, trying hard...speaking was a kind of effort...his voice was nervous in some way, he wasn't inside, he felt pain."

Patterson also seemed excited when Simon detailed her relationship with her parents, especially Don's intimacy.

"She's especially with her dad, they share a lot of knowledge, learning and interests in the world, and I think she likes his gentle nature."

"Mom and Dad are really active in having a good relationship with Erin (although separate) and I think it's mutual."

Simon also detailed his conversation with Erin, who, after lunch, was also sick to her, including her repeated telling him that she was worried that she would “pop her pants” because of diarrhea.

He talked about a conversation the couple had with their children at Monash Hospital, where Erin and the children were treated after lunch, when they discussed Erin’s blind taste tests for muffins cooked with dehydrated mushrooms.

She said their youngest child doesn’t like mushrooms, which is fun, and he likes to use dried mushroom muffins.

Prosecutors accused Patterson of not feeling uncomfortable because of lunch. The court was also told Tuesday that prosecutors would not suggest there was no particular motive for alleged murder and murder.

Patterson's Colin Mandy SC said she accidentally poisoned lunch guests and was not trying to hurt any of them.

After cross-examination, Simon said Erin offered each of his three siblings and their partners hundreds of thousands of dollars in loans to allow them to buy a home.

Simon said the loan has no repayment schedule, only an interest in inflation.

He also said the couple traveled with their children after they separated in 2015, including trips to South Africa, Botswana, Darwin, Adelaide, New Zealand and South Australia.

Simon said there was another attempt to reconcile after a trip to Africa in 2018.

Still, he was involved in the design and talked with a builder about the house Patterson intended to build in Leongatha, where lunch was held about three years later.

Simon believes that while the design of the house is centered on the ideal that is suitable for children to grow up, it also reflects the prospects for a shared future with him and Patterson.

He agrees that Patterson is a devout mother who relies on his extended family, including his siblings and their partners as support networks.

Simon agrees that Patterson imposes weight in their relationship, but doesn't think she's embarrassed about it.

"Are you unhappy with her appearance?" Mandy asked.

Simon replied: "I don't think Erin is happy with her situation, including most aspects."

“I don’t think she has a high self-esteem.”

Simon confirmed that the child support he had to pay Erin was $40 per month, which created some "friction" because that wasn't enough.

Simon also talked about joining Patterson in South Gippsland with friends before falling in love with each other.

He said that although he knew Patterson was an atheist, she showed up for the service.

“She was moved by the communication part of the service rather than the preaching,” Simon said.

"The religious or spiritual aspect of what happened on that date?" Mandy asked him.

"Yes," Simon replied.

Morwell's trial continues, with Simon's evidence expected to end on Friday.