This led to the Ukrainian President walking out of the White House, canceling the scheduled meetings .

I don't know which news reports you are reading, but that is not what happened. This is what happened: Zelensky was told to leave. He wanted to stay and negotiate, but with lunch getting cold in the hall, he was escorted out of the building. I heard an interview with Waltz where he confirmed he had told Zelensky to leave.

AP
The Ukrainian leader was asked to leave the White House by top Trump advisers shortly after Trump shouted at him, showing open disdain.

Jerusalem Post:
The national security advisor and Secretary of State Marco Rubio both asked Zelensky to leave the White House after the meeting, according to Waltz

As an American, I was embarrassed. It was hard to watch that display of crass bullying by Vance and Trump.