It takes Jake an embarrassingly long time for him to notice that Jeremy has vacated the premises.

In his defence, he expected Jeremy to.

You know.

Show up. In front of him.

Or something.

So it takes him an embarrassingly long time to notice that Jeremy has vacated the premises and that he can move but when he does notice it he groans. "Jeremy!" he calls into the empty air. Jeremy's being dramatic, isn't he. The whole reason Jake tried to communicate that he was staying was so that they'd skip it!