Barnaby Joyce's 'increasingly suspicious' wife made probing phone calls to his staff while Vikki Campion worked in his office - culminating in a blazing, door-slamming row.
Political insider Niki Savva has laid bare the unravelling of the former deputy prime minister in her new book, Plots and Prayers, which documents the end of Malcolm Turnbull's leadership and the rise of Scott Morrison.
In the book, Ms Savva writes that Mr Joyce was spotted with Ms Campion at a doctor's surgery for 'scans' in early 2017. Mr Joyce's 'mood swings' were obvious to everyone around him during this time, she said.
Meanwhile, back in the office Ms Campion, who was hired in mid-2016, spoke frankly to her colleagues about her 'closeness' with the deputy prime minister, telling fellow government staff about the bushwalks they went on together.
Ms Savva, a former press secretary to ex-Treasurer Peter Costello, said: 'She made no secret of her closeness to Joyce.
'She would describe him as the loneliest man in Parliament.'
New life: Barnaby Joyce with his new partner Vikki Campion and sons Sebastian (on right) and Thomas (cradled)
Final public appearance: Mr Joyce with his wife at the 2017 Midwinter Ball that June. Ms Savva writes that the pair had a blazing row months before this photo was taken
When Natalie Joyce started asking questions of Mr Joyce's staff, Ms Savva wrote, 'it put them under enormous pressure, deepening their emotional and ethical conflict, and sorely testing their loyalties.
In February 2017, Mrs Joyce, who 'had access to her husband's diary and could see the frequency of his travels with Campion', headed to Canberra to 'try to find out what was going on.'
'Once in the office, she quizzed an uncomfortable (Diana) Hallam (Mr Joyce's chief of staff) about her husband's activities, and then threatened to confront Campion,' Ms Savva wrote.
Mrs Joyce then confronted her husband directly, Ms Savva recalled.
She (Ms Campion) would describe him as the loneliest man in Parliament
'Staff cringed as doors slammed.
'They could not hear what was being said, but they could hear the couple yelling, and then saw the distressed expressions on their faces when it was over'.
A statement then-acting prime minister Mr Joyce gave the media about having to fly to Canberra, instead of home in Tamworth, that May also sparked speculation.
Natalie Joyce and the couple's daughters (from left) Odette, Bridgette, Caroline and Jules
Historical photo: Joyce and family upon his election as a senator in 2005
'I was happily on my way back to Tamworth until my media adviser told me