Here's what happened inside the White House after the Oval Office shouting match:
Trump huddled with his key advisers immediately afterward inside the Oval. According to a White House official, Trump consulted Vance, Rubio, Bessent, etc. That was when Trump decided that Zelensky was "not in a place to negotiate."
He directed Secretary Rubio and his national security adviser Mike Waltz to deliver the message: it was time for Zelensky to leave. The Ukrainians were holding nearby in a separate room. (That's standard for foreign leader visits.)
Typically they reconvene for lunch. But the Ukrainians would not be dining at the White House. As the prepared food sat nearby on carts in a hallway, the Ukrainians were instructed to leave.
The White House official said the Ukrainians wanted to continue the talks. But they were told no.
Zelensky left shortly thereafter.