Political careers ordinarily survive marital strife. But Don Brash is not an ordinary politician.
Gifted in some areas - dare one say at personal relationships - he is not an instinctive or astute political manager: think Exclusive Brethren; racing cars; emails; planks.
The National leader's track record would suggest he has the potential to turn his current marital difficulties into a disaster.
He has certainly managed with a little help to terminate the best run his party has had since becoming leader - on the election spending issue.
The first question to ponder is whether Dr Brash genuinely wants to continue or whether the intensity of stress that marital strife inevitably brings, doubled by the public glare, might dull his drive to become Prime Minister.
Yesterday he called on Bryan Sinclair, the young strategist he roped in in 2003 to help him to wrest the leadership from Bill English.
The fact that he has sought Mr Sinclair's help suggests he wants to continue, that he wants advice on how to survive the potential white-anting that opportunistic elements in the party may seize upon. The whispering has already begun.
The second question is whether his caucus genuinely wants him, and that depends on Dr Brash himself and whether he can keep his MPs' respect.
But it is their political respect, not moral respect, that will mostly count - except perhaps for Brian Connell, the moral conservative who confronted Dr Brash in the caucus on Tuesday and made the affair news.
Dr Brash has not been a crusader on morality issues so he is hardly a fair target on that count. His previous reference to Helen Clark's "indifference towards the institution of marriage" is hardly the quote that is going to hang him.
His vulnerability runs deeper.
His credentials and his value to National after 14 years as Reserve Bank Governor is his trustworthiness.
It hasn't mattered beyond the Beltway that he is hopeless in the House because he is the anti-politician who is too honest for his own good. People believe him. His strength has been in his character.
After becoming leader and in the election campaign he willingly cashed in on the "happily married" image with his adoring Je Lan. And we all know the pride he took in the fact that his wife came from Singapore.
There will be a great deal of sympathy for the couple, but there will also be questions about his integrity and his judgment.
Dr Brash told the caucus on Tuesday he had not lied to the New Zealand public. They, not him, will be the judge of that.
<i>Audrey Young:</i> Integrity, judgment brought into question

Opinion by Audrey Young
Audrey Young, Senior Political Correspondent at the New Zealand Herald based at Parliament, specialises in writing about politics and power.
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