Thanks for the info but you're wrong about Zaphod and Trillian's motivations for leaving.
It was the other guy, the psychiatrist who wanted to see the Man Who Ruled The Universe. Once Zaphod and Trillian saw the Man could take care of himself and the nosy psychiatrist, they left with Zaphod saying to Trillian, "I think the Universe is in good hands."
The Man Who Rules The Universe senses Zaphod and Trillian were no friends of the psychiatrist so he distracted the guy when he heard the sound of Zaphod's spaceship taking off and after that he left the psychiatrist out in the rain, knocking on his door.