Whereas Hamlet has been insistently demanding that she clean up her act, thrust aside lust, and “assume a virtue, if [she has] it not”—in a word, that she give up on her desire—he suddenly backs down. He seems to do so at the very moment at which he senses her acquiescence, and no doubt precisely because she seems to be acquiescing.
Hamlet makes a demand upon her—throw the toad out— and yet as soon as she begins to yield, he says, “forget it.” In response to her “What shall I do?” he replies: “Not this, by no means, that I bid you do.”