Despite a recent diplomatic charm offensive
in Brussels, she has not moved much closer to unlocking the second phase of EU exit talks, which would see the parties discuss their future relationship -- including a potential new trade deal.
At this moment of frustration for May, one of the great ironies of the UK's vote to leave the EU last year is becoming clearer: the monumental effort and time her government now needs to devote to Brussels is more so than perhaps all previous post-war UK administrations.
That means 52% of Brits who voted in favor of cutting ties with the EU are now watching as May and her team devote huge attention to Europe -- with a key strategic priority being developing the new relationship with the 27 other member states.
Such is the scale of the task underway that it may be the most complex and important peacetime negotiations that the United Kingdom has ever faced.
Part of the reason why the challenge is so big is that, as recent analysis from LSE IDEAS reveals, the Brexit vote triggered not one, but 14 overlapping negotiations
to contend with.
Collectively these comprise discussion centered within the United Kingdom; between the United Kingdom and the EU; within the EU; and also internationally beyond Europe; and are potentially very protracted.
Almost 18 months into May's premiership -- even after her big speech in Florence
last month -- the country remains little wiser about the likely pathway toward the EU exit door. This includes key details of what the alternative model is she wishes the UK to adopt with the EU.
To much of the rest of Europe, Brexit Britain has sometimes felt like one long comedy fast turning into farce, if not tragedy.
To be fair to May, the scale of the challenge she faces isn't all of her own making, given that she inherited as prime minister no formal EU exit planning because her predecessor David Cameron refused to contemplate losing last year's referendum.
As May is fast discovering, the complexity of the negotiations that she must undertake now with no House of Commons majority means the government will find it hard to negotiate an alternative model that can secure consent from Brussels and the EU member states, which comes close to providing the same balance of influence and advantages that the United Kingdom gets from its current full EU member status.
For all the EU's flaws -- and it has many -- the United Kingdom has enjoyed a uniquely positive position in what is the world's largest political and economic union. For instance, it has all the benefits of the Single Market, but is not part of the single currency, and it has retained a big budgetary rebate.
The stark reality is that, while the nature of existing agreements with the EU vary from Norway to Switzerland and Canada and Turkey, all have key disadvantages. None of them, for example, provide full access to financial services within the single market, which accounts for around 80% of the UK's economy.
Moreover, Brexiteers continue to generally shy away from the implications of what even access to (let alone membership of) the Single Market may entail without full EU membership.
Take the example of Norway, which has considerable access to the Single Market. In exchange, it is required to adhere to EU rules without having a vote on them as the United Kingdom does now. It accepts free movement of people, makes contributions to EU programs and budgets and still is required to do customs checks on goods crossing into the EU.
Moreover, preferential access to 53 markets outside Europe with which the EU has free trade agreements will come to an end with Brexit -- or need to be eventually renegotiated bilaterally in coming years.
And outside of the economic realm, May knows that forthcoming discussions offer no guarantees that the United Kingdom could fully replicate existing cooperation in areas like policing and security -- which she has previous cited as important.
Taken overall, the realization is spreading within the UK that more of its government's resources and attention needs to be directed toward the EU than ever before.
This irony is compounded by the fact that, despite all of this effort, May will struggle to strike a deal that is better for the UK national interest than one which continued membership of a reformed EU potentially offers.