Lance Partridge was a close friend of Mathew Dunbar for years before he was found dead on his property Pandora in the Northern Tablelands town of Walcha in the early hours of August 2, 2017.

Mr Partridge told the Supreme Court jury that Mr Dunbar was "extremely happy" after Natasha Beth Darcy, whom he met online, moved into his property in October 2016, and the two set about tending to the farm and house together.

Mr Dunbar, who was using anti-depressants, had suggested Mr Partridge or another close friend may one day inherit his $3.5 million property, the jury was told.

Darcy, 46, has pleaded not guilty to murdering the 42-year-old sheep farmer after he was found gassed in bed with a plastic bag over his head.

Chloe Hoy, who lived next to Pandora, said her openly gay brother-in-law called her intoxicated in 2014 to mention his "intimate issues" with Mr Dunbar and how the men would handle it if they were to have a future together.

However, she said there was no mention of anything of a sexual nature and she took the "future together" to be a reference to a specific business venture, Ms Hoy told the court.

Mr Partridge chuckled when asked if Mr Dunbar had ever raised concerns of contracting HIV.

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

"Matt was a hypochondriac."

Ex-girlfriend Tanya Morley also wrote in her police statement that she knew about a Walcha man Mr Dunbar was in a relationship with, but was unsure how long it lasted.

Ms Morley began dating Mr Dunbar towards the end of high school about 20 years ago, and the two remained in contact until his death.

She said all text messages he sent to her were signed off with "I love you always and forever," and that she often replied "I love you forever honey," but said they were just friends at this point.

At times Mr Dunbar's tone of voice and conversation over the phone would change, saying words to the effect "I can't really talk because she's around".

Darcy messaged Ms Morley on Facebook in June 2017.

"There's nothing going on between Matt and I," Ms Morley texted back to Darcy.

Soon after, Mr Dunbar let Ms Morley know he was not allowed to contact her anymore.

"I asked him 'was it because of Natasha?' He indicated it was, yes," Ms Morley said.

She was then blocked from contacting his Facebook account.

Another farming friend of Mr Dunbar's testified that he had cautioned him about his relationship with Darcy, but that his advice was rejected.

His first contact with Darcy was when she advised him of Mr Dunbar attempting suicide, saying police had come to confiscate his rifles and that she was hiding his medication which he found "odd".

In 2015 Mr Dunbar made a new will leaving all of his estate to Darcy, which is why she allegedly used a Nutribullet to blend sedatives into a drink she gave him before covering his head, prosecutor Brett Hatfield earlier said.

But her barrister Janet Manuel SC contends Mr Dunbar had health problems, depression and had previously made a suicide threat in June 2017.

The trial continues before Justice Julia Lonergan.

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Australian Associated Press