One thing it was not, however, was much of a shock, even if her car crash along a coastal road in the capital was probably not the way many thought her ministerial career might end.
The lurid details of the accident, and what happened on Sunday evening leading up to it, are now being picked over by media.
While backbench MPs come and go quite regularly from Parliament for various reasons, the disintegration of a minister under the spotlight of the nation is a much more extraordinary matter.
When that minister is the Minister of Justice, and is arrested and taken into police custody for allegedly breaking the law, then that cruel spotlight will be shone even harder on them.
For someone who is by all accounts a highly capable politician to be brought so low by mental health issues and extreme anguish is unutterably sad.
Clearly Ms Allan was not as ready to return to work as she, and others, thought.
It is entirely possible she was misguided by a false dawn and once again felt able to operate at the very high, and exhausting, level expected of politicians.
She — and haven’t we all done this to a certain extent? — may have over-optimistically judged she was now fit for duties and convinced herself she would be able to cope with Parliament, one of the toughest and least supportive work environments there is.
Unfortunately, recovery from mental illness is rarely so kind as to be linear.
The healing can be unpredictable, and while there can be small steps forward, there are often steps backwards too.
Some blame for Ms Allan’s demise as a minister has been directed towards Prime Minister Chris Hipkins.
When you’re the boss, you ultimately get blamed for most things, but such criticism in this case is totally unfair.
But if she said she was, unless he had good medical evidence to the contrary, he could hardly tell her to stay away.
Indeed, the prime minister reiterated on Monday that Ms Allan had been "at the top of her game" in Parliament last week.
He said he was "gutted" for her and concerned about her wellbeing, and that while her actions on Sunday night were indefensible, particularly as justice minister, he understood she was in a state of "extreme emotional distress" at the time.
Several ministerial colleagues also spoke out about Ms Allan. Education Minister Jan Tinetti told reporters the news was devastating and she was "so worried about my friend right now".
It is encouraging that politicians from across the House have expressed concern and sympathy for Ms Allan, and sent her their good wishes.
However, it should come as little surprise that some in Opposition are making political capital out of this wretched event and claiming it is another nail in the Labour Government’s coffin.
National Party leader Christopher Luxon queried why the prime minister let her return to work and said something was going wrong with the culture of Cabinet, citing a series of ministerial appointments which had gone haywire.
One has to ask, how well did National manage former leader Todd Muller’s mental health issues?
For Mr Luxon to expect Mr Hipkins to be some sort of soothsayer, and blame his leadership, seems faintly ridiculous.
So can we fairly say this may be the last straw for voters and that the crash on Evans Bay Parade will see the fall of the Government and victory for National in October?
We would like to think most Kiwis realise an individual suffering from mental illness is not reason enough to elect a new government.
Ms Allan is now back home with whānau in her East Coast electorate. We wish her all the best for a speedy recovery.
And as many of us with any knowledge of mental illness might say, there but for the grace of God go we.
