The mixture of emotions that Jareth had been feeling as he thought Peter dead (amusement, hope for his future with Sarah, and an overwhelming sense of irony) turned to anger when he realized that the man was indeed very much alive. It was almost cruel, to be granted a glimpse of his life without Sarah's boyfriend marring it, and then to have him back again, to have Sarah clutching him and sobbing and babbling like a child.
One of his goblins was unfortunate enought to get too close to his foot (they, after all, cared little for the dead then alive human, as they were still in the midst of their very heated debate) and Jareth kicked the thing across the room. He might not be able to kill the boy, or to convince Sarah to come with him, but one thing that he could do was intimidate his subjects. "I said get out!" He all but roared. "And not to listen to any order that you know full well will clash with one of my own." He looked down at the embracing pair again, all but wincing. He had to leave, and soon or he was going to be ill. He wasn't worried about Peter's retribution, as Jareth had already learned that his crystals worked quite well at deflecting things, but he wasn't sure how much more of this he could stand. Sarah was his, and while he wasn't quite desperate enough to force her to come with him, to kidnap her, he wasn't strong enough to watch her cling so strongly to another either.