Prime Minister Malcolm Turnbull says he and wife Lucy are acutely aware of the hurt Barnaby Joyce's marriage breakdown has caused his estranged wife and daughters.
Mr Turnbull would not be drawn on reports the deputy prime minister's new partner and former staffer was offered a posting in a colleague's office last year, saying he did not want to publicly discuss private matters.
"It is a tough and distressing episode and I am very conscious - Lucy and I are very conscious - of the hurt occasioned to Natalie and their daughters in particular," he told reporters in Canberra on Friday.
"So that's why I don't want to add or contribute to the discussion about it."
The prime minister rejected the need for Australia to follow the United States and ban ministers of parliament from sleeping with their staff.
"Relations between consenting adults is not something that normally, you would be justified in, if you like, seeking to regulate," he told reporters.
"Adults can conduct their relationships - if it's consensual, respectful - that's their right."
Mr Joyce's partner, Vikki Campion, was reportedly assigned a digital and social media position in the office of Nationals MP Matt Canavan and was not replaced in the months after she left.
Cabinet minister Christopher Pyne is confident the appointment was above board, saying "maybe that's the job that Matt Canavan wanted in his office at that time".
"I'm not in the gun on this story and I think it's highly unlikely anything untoward occurred," Mr Pyne told the Nine Network on Friday.
"I'm sure it was all entirely appropriate, but again that's a matter that Matt Canavan needs to respond to, not me."
The Daily Telegraph on Friday cited a spokeswoman for Senator Canavan, who was resources minister at the time, as saying Ms Campion was "suitably qualified" for the role given her work history.
This week it was revealed Mr Joyce, 50, and a pregnant Ms Campion, 33, are now in a private relationship.
Labor frontbencher Anthony Albanese said staffing was a matter for the government and he was not aware of the circumstances or details.
In July, Senator Canavan, who once worked as Mr Joyce's chief of staff, resigned his ministry after issues were raised about his eligibility to sit in parliament.
Once those were resolved, he returned to the frontbench in October, again as resources minister.