P.E.I. voters have spoken, and it’s more bad news for Prime Minister Justin Trudeau. Premier-designate Dennis King, elected PC party leader a scant two months ago, won 12 seats in the Island’s 27-seat legislature, putting him in place to form a minority government.

After three terms in office, the incumbent Liberals were reduced to six seats — while the upstart Green Party scored an impressive eight to form the official opposition, the first time Greens have held this position in a Canadian Parliament.

READ MORE: Prince Edward Island voters elect PC minority

King’s victory marks the fifth time that voters tossed a provincial Liberal government since Trudeau took office. B.C. was the first stronghold to crumble, when the NDP’s John Horgan bested Liberal Christy Clark in 2017. A year later the dominoes really started to fall, with Ontario, New Brunswick and Quebec all shedding their Liberal rulers within the space of six months. Out went Liberals Kathleen Wynne, Brian Gallant and Philippe Couillard; in came Progressive Conservatives Doug Ford and Blaine Higgs, and the populist Coalition Avenir Quebec leader, Francois Legault.

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Compounding Trudeau’s woes was the election of United Conservative Party leader Jason Kenney last week in Alberta, replacing the NDP’s Rachel Notley. Together with Ford, Higgs, Manitoba PC Premier Brian Pallister and Saskatchewan Party Premier Scott Moe, Kenney and company now present a veritable blue swamp in which Trudeau threatens to founder. Add P.E.I. to the mix, and there are now only three Liberal premiers left in the country. That number could be reduced to two on May 16, when Newfoundland and Labrador goes to the polls. If Newfoundland votes Tory, then there will be seven right-of-centre governments staring at Trudeau around the federal table — and you can bet they won’t be smiling.

WATCH BELOW: PEI is the latest province to go blue, but Greens come in second

1:51 P.E.I. becomes latest province to go blue, but Greens come in 2nd causing shift in Canadian politics P.E.I. becomes latest province to go blue, but Greens come in 2nd causing shift in Canadian politics

What a change from the 2015 election campaign, when Trudeau couldn’t get enough of the provinces. “The challenges we face cannot be solved only from Ottawa,” he wrote in a letter to then-Quebec Premier Phillippe Couillard. These challenges, he continued, “require a true partnership between the federal government and the provinces.” To do this, Trudeau made a number of grand promises. He pledged to revise the equalization framework, forge a new health care deal, and hold regular First Ministers Meetings, in contrast to then-PM Stephen Harper, who held all of one, in 2009, in his nine years in office.

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Things started off on a sunny note. In advance of the COP21 Climate Meeting in December 2015, Trudeau convened provincial and territorial leaders to forge the “strong and cohesive message we will be delivering as Canadians in Paris.” The New York Times crowed that in “less than a month, Canada has executed a complete about-face on global climate change.” It waxed eloquent about Trudeau’s efforts to bring the provinces onside, particularly the grand bargain he would be striking with Notley, who along with several other premiers was to join Trudeau in Paris.

That bargain — and all the goodwill Trudeau sought to create — has come completely undone in the ensuing years, through a combination of missteps by the prime minister and the competing agendas of conservative provincial parties. Buying out Kinder Morgan’s twinning of the Trans Mountain pipeline with over $4 billion in taxpayers’ money — while pledging to respect indigenous rights and protect the environment — is the wound that still festers. Forcing the carbon tax on provinces that didn’t want it not only created a rift with Ottawa but a united front among opponents.

READ MORE: Trudeau has heated moment when asked to reconcile climate plan with pipeline purchase

In short, Trudeau’s attempt to have things “both ways” on the environment and resource development have resulted in him getting neither. Instead, environmentalists and oil workers alike mount protests against his government. Regional tensions run high both east and west. B.C. and Alberta are at each others’ throats, half the country has declared war on the carbon tax, and Quebec is demanding more powers on taxation and immigration. Trudeau’s dream of a “true partnership” between the federal government and the provinces is officially dead.

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And as the 2019 federal election looms, this fraying of national unity may be Trudeau’s greatest failure. Prime Minister John A. Macdonald famously described the process of uniting Canada’s disparate interests as “herding cats” when he was bringing the provinces together into Confederation. Macdonald biographer Richard Gwyn identified it as the defining quality of a great prime minister, one which hasn’t changed to this day. “If you’re going to run Canada, which is a very decentralized, diversified country … you’ve got to be able to convince people to go along with what you want, what you think is right for the country as a whole, and that takes a lot of skill, a lot of art, a lot of deviousness, and resilience.”

COMMENTARY: Seat projection shows Trudeau Liberals slip out of majority position

The past four years have revealed that Trudeau possesses none of these things. He cannot even manage the disparate elements of his own caucus and cabinet, never mind the nation. And Canadians have finally caught on.

Six months to the election, polls have the Conservatives leading the Liberals by a slim margin. Seat projections show the Liberals slipping into minority territory. And now the Greens are feeling their oats.

In a marriage like Canada’s, sunny ways are like love: they just aren’t enough to keep everyone together. Maybe it’s time to change partners.

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Tasha Kheiriddin is the founder and CEO of Ellipsum Communications and a Global News contributor.