He might reasonably have believed when he left for Tuscany that his reunion with the voters of Britain would be a tender one. Four months into a marriage, it is the least a groom can expect.
Instead, though, he will return to find the Scottish wedding party waging family warfare, the Montserrat contingent complaining loudly that they did not get a big enough slice of the cake, and the mortgage on the marital home threatening to spiral out of control.
Mr Blair's love-affair with the electorate is not over yet, of course, but could the honeymoon be coming to an end?
After the unbounded joy of May, the warm glow of June and the post-Budget self-congratulation of July, August has not been the kindest of months. It never is, of course. In the empty dust-bowl left behind when politics heads for the seaside, even the most minor mishap can whip up an eddy of bad publicity or even a full-blown whirlwind. When John Prescott jokingly named a Chinese mitten crab after Peter Mandelson last week, for example, he can hardly have expected front-page headlines in every newspaper.
It has not all been silly season nonsense, though. The suicide of Gordon McMaster and the subsequent suspension of another MP in Paisley, the row over compensation for the volcano-hit West Indian islanders and a fourth rise in interest rates since the election have all done their bit to tarnish the Government's shiny new image.
But if the Prime Minister is tempted to heave a sigh of relief that he was out of the country when the champagne went flat, he should restrain himself. August may have brought a few notes of discord between the Government and its electors, but September just might see the shedding of the first real tears.
There will be mutterings at the Trades Union Congress about the future of Labour's relations with the unions. The victory celebrations at the party's Brighton conference will be marred by a row over Mr Blair's plans for further modernisation. And there will be the potential for real trouble as voters in Scotland and Wales go to the polls to make their decisions about devolution.
A vote in favour of a Scottish parliament but against the granting of tax-raising powers, for example, would be deeply embarrassing (and very troublesome) for a government that has put its full weight into the campaign for a "yes, yes" vote. And even a narrow victory in Wales would leave behind it the uneasy sensation that a major change is being pushed through without wholehearted public support.
As the autumn drags on, there will be pitfalls aplenty for Mr Blair's new government. Paisley may have seemed like a nasty accident in the middle of August, but it could well become a running sore before Christmas as the extent of corruption in other Scottish Labour Party branches becomes clear. Already the Tories have made capital out of the suspensions of the Govan MP Mohammed Sarwar and the West Renfrewshire member Tommy Graham, but there may be more to come when a forthcoming report on Labour in Glasgow is published. Any one of four or five other low-level rows grumbling on across Scotland may easily blow up into a major incident before the year is out.
The economy will also be back to haunt the Government as the nights draw in. There were comforting noises after the summer interest rate rise, to the effect that the situation would now remain stable; but just a couple of weeks later, the hint of yet another hike is being glimpsed on the horizon.
Exports will continue to suffer; and the feel-good factor will not be so abundant in December, when home-owners are facing yet more rises in their mortgage payments.
The high-profile millennium project may well cause a headache or two, as well. Mr Mandelson's decision last week to spend an extra pounds 8m on the roof of the dome may have passed off relatively quietly, but he is not out of the woods yet. Who will take the flak when the bill for the exhibition begins to enter the stratosphere? Will Mr Blair still be out of the firing- line when public unease turns to real anger?
The dead of winter will see the return of some of those perennial problems from which it was Labour's wont, in opposition, to make capital out of at the expense of the Tories. This year Labour will pay the price when a flu epidemic stretches hospital services to breaking-point and doctors complain that the sick are dying because of a lack of funds. This year it will be the Tories who cash in when teacher redundancies lead to another rise in class sizes, and when schools complain that they still cannot afford to buy the books they need.
There will be other problems, too. The Northern Irish peace process hangs in the balance, and the BSE crisis, which was once the Tories' bete noire, could soon become a trial for Labour as thousands of carcasses wait in warehouses to be incinerated. Students who will be expected to pay pounds 1,000 per year in fees from next year cannot be expected simply to swallow the charge without further protest, and it is conceivable that they will find allies among some of Tony Blair's backbenchers.
Of course there will be no flag-waving crowds in Downing Street this week, not least because most of the party hacks who staged the demonstration last time are still away on their holidays. Tony Blair should not be surprised by any of this. The truth of the matter is that normal politics has been resumed.
When Gerald Ford was elected, he told Congress: "I do not want a honeymoon with you; I want a good marriage."
New Labour, on the other hand, chose to go for full-blown, dizzy-headed euphoria. It worked for a while, but nobody ever seriously thought it was going to last. And the bigger the party, the bigger the headache the morning after.