It must be difficult when those driven by environmental awareness or climate change concerns were, for too long, banished to the fringes of British politics only to find that, when they reach centre stage, others with more political clout have taken up the banner.
So perhaps it is the fact that climate protection policies are now mainstream, and central to the offers of other parties, including my own, which has promoted the change.
Or maybe it is the limitations of being a junior partner in government which persuaded the Greens to allow a cause different from the one on which they were founded – and has drawn so many - to replace their top priority.
Like their more senior nationalist partners at Holyrood, the party’s leadership has declared that if there is no second referendum on Scotland’s future within the UK, they will fight the general election solely on the constitutional question.
Or to put it another way.
If they don’t get their way, they will re-define the General Election to suit themselves, calling every vote cast for a Green candidate as a vote for independence.
Not for the fight to save the planet mind you, but for the one to destroy the UK.
I find that an astonishing assumption.
To say that you are able to define the intent behind every single cross in a box is as arrogant as it is foolish.
Not so much perhaps for the SNP whose entire raison d’être is separatism, but for a party with a different founding and overarching principle it is a bit of a stretch.
Not to mention a let down for many who voted for them.
Last year, a poll by Lord Ashcroft found that 43 per cent of those planning to vote Green supported independence while 46 per cent were against it.
I don’t find that figure at all surprising since many of us are convinced that it is internationalism and global action which has the only hope of tackling the climate-related fire and flood which is ravaging communities across the planet.
But it is perhaps one that the Green Party would have done well to take heed of before they hitched their wagon so conclusively to the nationalists.
The desire to pursue policies which will protect the planet and reverse the rising temperatures and sea levels is one which stretches across the political spectrum.
Decarbonisation has become a watchword of parliamentarians on both sides of the house at Westminster.
I am both a Liberal Democrat and a firm believer in the need to address our climate emergency, as witnessed by the emphasis our party policy now puts on these issues.
Climate protection and nationalism are not exclusive bedfellows.
Over the years, I have spoken to countless green-minded voters on doorsteps across the country who assured me that they saw their future in the United Kingdom.
My own political experience tells me that when the Green membership voted to approve a deal with the SNP, they will have done so in the hope that their values and beliefs could be shaped into policy with the power to change lives.
It is a feeling that I remember only too well.
And it is the hope, I know, that kills you.
We, the people of Scotland, were promised that this arrangement at Holyrood would be good for us all.
A revolution of climate and social policies that would change our lives. Thousands of jobs created by a just transition at a pivotal moment in our history.
The First Minister Nicola Sturgeon, and her Green ministerial subordinates Patrick Harvie and Lorna Slater, graced our news outlets like newly crowned lottery winners as they announced that ‘not quite coalition’ agreement.
A happy day for both, as the Greens offered the SNP a brand new shiny bow to brighten up their tattered government offering.
In turn, the Greens seemed delirious with the hope that the power they gained created.
And yet a fraction more than a year later the sparkle has begun to fade and the agenda has changed.
Activists who have spent decades awakening us all to the dangers of global warming now find that those in whom they placed their faith have become merely a bit player in the separatist narrative.
For the past decade and a half of SNP rule, Scottish politics has been governed by two different factors: actual policies and nationalism.
When the first fails the second is rolled out as a metaphorical fire blanket to dampen the anger while a target is found to redirect blame towards.
Usually, they call it Westminster.
Ironically, ignoring the fact that instead of being the stronger voice for Scotland there, which the SNP once promised, they are simply the whining voice of nationalism.
It is a tactic which provides a green light (if they still call it green) to the governing parties to perform badly.
Not exactly the progressive politics they preach.
But that is where we are, yet again. Surely none of us can be unaware of the crisis facing our NHS with long waiting lists, staff shortages and immense pressure on all those on the front line.
The level of drug deaths is shameful and little changed. Our teachers are stretched.
All of us are feeling the increasingly bitter chill of the economic crisis which threatens to engulf us. And the planet is burning.
We need answers. Action. Policies. The whining has to stop.
At a general election, whenever it comes, all politicians should put peoples’ well-being and the future of the planet before any other narrow agenda.
This time the nationalist fire blanket won’t work.