A jury heard Mr Dunbar threatened suicide after an argument with Darcy about money he had lent to former lover, Tanya Louise Morley.

Messages between Ms Morley and Mr Dunbar tendered as evidence in the NSW Supreme Court reveal he would often sign off messages with, 'I love you always and forever'; to which she replied, 'I love you forever sweetie' until she was blocked at the request of Ms Darcy.

At the time Ms Morley was, and is, in a relationship of her own and lives in Queensland.

She said the tone of Mr Dunbar's conversations changed when Darcy was around.

"He told me he wasn't allowed to contact me anymore and we had to cease contact," Ms Morley said.

"I asked him if it was because of Natasha and he indicated that yes, it was.

"Shortly after that I was blocked completely from Facebook, which means I wasn't able to message him or anything I was completely blocked."

Darcy is accused of murdering Mr Dunbar at his property Pandora in Walcha by sedating and gassing him.

It's the Crown case that Darcy searched 'how to commit murder' before she allegedly used a Nutribullet to blend a cocktail of drugs that were given to Mr Dunbar before he was gassed.

Darcy was the sole beneficiary of Mr Dunbar's property, which the court hard was sold in 2019 for about $4.65 million.

Mr Dunbar's previous relationships were at the centre of questioning on day four of the trial.

The court heard Mr Dunbar had struggled with "erectile dysfunction" in some of his relationships with women and despite the fact he "would have loved to have a child" he was unable to conceive.

Old family friend and executor of Mr Dunbar's estate, Lance Partridge, gave evidence that Mr Dunbar had also had a relationship with a man but that it wasn't successful.

"They spent all day sitting in the poultry shed at the Walcha Show together, I know they went on a holiday together but I don't think Mathew participated in a sexual act very well with him from what Mathew told me," he said.

"Mathew only had one relationship with a male and it wasn't successful, he wasn't gay."

Read also:

Defence solicitor Janet Manuell SC asked a number of witnesses about Mr Dunbar's alleged prior relationships with men.

It is not proven at this stage that Mr Dunbar had relationships with men, except for the evidence given by witnesses that they were aware of a relationship he had with a man prior to meeting murder-accused Darcy.

Neighbours to the property and a pharmacy worker gave evidence on Wednesday and statements from veterinary clinic workers in Armidale were read to the court.

The trial continues before Justice Julia Lonergan.

Our journalists work hard to provide local, up-to-date news to the community. This is how you can continue to access our trusted content: