Over the past two seasons, Shawn and Juliet have developed a romantic relationship to the point, in last week's episode, Juliet realized Shawn was not psychic. Most of the characters believing Shawn's act is Psych's most playful concept and the one viewers have to swallow to watch the show at all. For Shawn and Juliet's relationship to reach its potential, though, Juliet had to find out and accept the truth.
Much of this week's episode played out in Shawn's head as he weighed reality, where Juliet found him out, against how things might have gone if she hadn't. The script and the actors played out both storylines seamlessly. In the end, Shawn was teased with a dream of Juliet coming to terms with his deceit and accepting him. He then woke up to Juliet asking him to move out.
I think this will play out like the tellings of Superman where Lois discovers Clark is Superman. At first, she's thrown for a loop. Having believed in who Clark seemed to be, she feels betrayed by the revelation of who he is. Shawn has it better than Clark. He hasn't built disparate identities. His thin lie about being psychic is the only phony thing about him.