And would it have been worth it, after all, Would it have been worth while, After the sunsets and the dooryards and the sprinkled streets, After the novels, after the teacups, after the skirts that trail along the floor – And this, and so much more? – It is impossible to say just what I mean!
He’s still thinking in worst-case-scenario mode. He wonders if it would have been worth it if after him and his love have experienced all of these nice but trivial pleasures of everyday, middle-class life, including "sunsets," "novels," and "teacups" – but he can’t finish his thought.
If we had to guess, we might say that he’s afraid that if his big question didn’t go over well, it would throw a wrench in his tidy, polite, inoffensive life. It’s the most bogus excuse in the book, like when you ask someone on a date and they say, "No, I don’t want to ruin our friendship."
But Prufrock is right about one thing: he’s totally incapable of saying what he means.
But as if a magic lantern threw the nerves in patterns on a screen: Would it have been worth while If one, settling a pillow or throwing off a shawl, And turning toward the window, should say: "That is not it at all, That is not what I meant, at all."
Ah, now he comes up with the right words to say what he means. It’s as if the words locked in his "nerves" were being projected by a "magic lantern" onto a screen for him to read.
But, in typical Prufrock-fashion, even the right words are disappointing. It’s just another image of a woman sitting on a couch or a bed and saying she has been misunderstood.
Once again, it is implied that he doesn’t think asking her would have been worth the risk of rejection.