And that's it...third-person triumphant!

Forget about not being able to tell "you" what you've always wanted to say...these two candidates for "wholeness" never even meet. As Derrida would say, no letter (especially not a love letter) ever reaches its destination. Each of us spends our entire lives trying to reduce that third person by one--and ramming our heads into "the girl" or "the boy" of our dreams. You can't tell the "whole truth" to a person that you aren't directly addressing, and no one has ever found that Northwest passage to "you".  The "shortcuts" (like the one that Camilla unveils to Diane after pulling her from the limo on Mulholland Dr.) aren't even paved with good intentions, but they do lead straight to Hell (which, Sartre to the contrary, is most definitely not "other people".) 

And that brings me back to the twin fantasies of pure communion (in love and in hate) that the film offers us--the first in Betty's impossibly poignant declaration "I'm in love with you" (the very expression of which exposes the unreality of her story and her supposed interlocutor) and the second in the consummation of Diane's plot to kill the (sublime) object of her desire... After each of these events, there is only Silencio--and the stark emptiness of a  box that isn't a box, but an airlock, sealed against the vacuum of radical otherness. There isn't anyone that wouldn't give their lives to be sucked up into that space--to address those emotions, at long last, to the appropriate place--but the words die still-born in a void. That's why "I" haven't told "you"--and maybe it's a lucky thing too!