Looking on the internet deeply has found these results:

is just that is the most popular phrase on the web.

it so happened 1568,000 results on the web	is just that 160,100,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
It so happened I was on my way to Aldebaran. So clever which, it so happened, it didn't work out! But it so happened he was speaking in a Protestant Church. It just so happened that the vampire never left. It so happened that when Finland's Prime Minister offered Russia help, the latter did not even agree to accept it. He made these preposterous statements to the great applause of his audience, which again, as it so happened, I observed on television. Now it so happened that at the very same moment, It so happened that our Zhenzi comes	an act. Rebecca... your birth plan is just that, it's a plan. The Commission's plan'D' is just that: propaganda, agitating and wheedling from top to bottom. It is just that Koman has a lover. But it is just that... history. It is just that I must believe in love. It is just that this feels like a sofa somewhat knotty. The big sister act is just that

it so happened

1568,000 results on the web

is just that

160,100,000 results on the web

More popular!

It so happened I was on my way to Aldebaran.
So clever which, it so happened, it didn't work out!
But it so happened he was speaking in a Protestant Church.
It just so happened that the vampire never left.
It so happened that when Finland's Prime Minister offered Russia help, the latter did not even agree to accept it.
He made these preposterous statements to the great applause of his audience, which again, as it so happened, I observed on television.
Now it so happened that at the very same moment,
It so happened that our Zhenzi comes

an act.
Rebecca... your birth plan is just that, it's a plan.
The Commission's plan'D' is just that: propaganda, agitating and wheedling from top to bottom.
It is just that Koman has a lover.
But it is just that... history.
It is just that I must believe in love.
It is just that this feels like a sofa somewhat knotty.
The big sister act is just that