It is safe to say that it would take something truly spectacular for Australians to vow off saying “g’day mate”.

But this week, the nation’s most beloved piece of vernacular took an unexpected, cringeworthy hit when it became embroiled in a sex scandal involving a fruit conference in Hong Kong, a website for “sugar babies” and an assistant government minister.

Andrew Broad, a married federal MP and assistant minister to the deputy prime minister, resigned from politics on Tuesday after it was revealed that he allegedly sent the beloved phrase “g’day mate”, in a sexually charged context, to a woman who claims she met him on a dating website. Broad has not responded directly to the allegations but has issued a media release.

The allegations caused embarrassment to the government and shone the latest spotlight on the governing Liberal and National parties’ perceived problem with women. They also prompted scores of Australians to swear off “g’day mate” for the foreseeable future.

The past year in Australian politics is now bookended by the resignation of one deputy prime minister, Barnaby Joyce – after an affair with a former staffer who became pregnant with his child – and Broad, the assistant to his replacement.

The Broad scandal is said to have began in Hong Kong, during an international fruit exhibition.

According to Broad’s own office, he was there on a work trip in September to support Australian farmers.

According to the woman in question, the MP texted her on WhatsApp and the two went on a date, after meeting on a website where wealthy older men meet women and provide them with gifts in exchange for company.

One particular screen shot of a series of WhatsApp messages alleged to be the exchange between the woman and Broad sparked a crisis of faith among Australians.

The screen shot shows the question: “Do you like Aussie accents?” to which the reply reads: “I love Aussie accents, I think they’re so sexy.”

The next message says: “I pull you close, run my strong hands down your back, softly kiss your neck and whisper G’day mate.” In other messages, it is alleged Broad said: “I’m a country guy, so I know how to fly a plane, ride a horse, fuck my woman. My intentions are completely dishonourable.”

Australians found the messages allegedly sent by Broad amusing and distressing in equal measure. Several people dubbed the unseemly exchange “fifty shades of g’day”. Others said the word g’day was “now cancelled”.

According to the woman, identified only as Amy in the women’s magazine that broke the story, he referred to himself as James Bond during their date but then complained about the prices at the expensive restaurant they were dining in.

Broad resigned from the ministry on Monday and from politics on Tuesday.

His seat, which he is not recontesting, could now be won by a female independent challenger, as voter backlash grows to the government’s perceived women problem.

Broad’s alleged behaviour fits with a pattern of the government refusing to promote women within the party and mistreating women outside it.

After the Liberal party toppled its own prime minister in a no-confidence motion in August, the then deputy leader, Julie Bishop – who had been deputy leader for 11 years – was eliminated in the first round of voting for a replacement.

In recent weeks multiple female MPs said they were subject to sexist intimidation and bullying from male colleagues during the contest as they rounded up votes.

Bishop then publicly spoke about the party’s “problem in attracting and maintaining women [and] diversity in general” and, in November, Victorian MP Julia Banks resigned from the party entirely, saying it treated women poorly.

Voters seemed to agree.

At the October by-election for ousted prime minister Malcolm Turnbull’s seat, the Liberal candidate, Dave Sharma, was defeated by independent candidate Kerryn Phelps in a huge upset. It was the first time the blue-ribbon seat was not won by a member of a conservative major party. Phelps also became the first woman to win the seat.

Broad’s scandal has also raised the memory of 2015, when another government minister, Jamie Briggs, resigned after allegations he acted inappropriately to a female public servant at a bar – also in Hong Kong.

Many are predicting an independent wave of female candidates at the upcoming federal election, scheduled for May next year.

Broad’s office was contacted by the Guardian on multiple occasions for comment. He has not made any comment as to whether the WhatsApp message were in fact sent by him.