What did Cecily do and pretend Algernon did it?

Algernon (Ernest in that moment for Cecily) tells to her about his feelings, as a consequence o that, he decides to propose to her. But, in that moment, Cecily says to him that he proposed to her three months ago. That means that, since that time they have been engaged. Later, also, she tells to Algernon that he wrote many pretty letters for her, and, that he bought the marriage ring. But really, that didn't happen in that way . The true is that some time ago, Cecily proposed to herself, and also she bought the ring and wrote letters by herselft,so, she pretended to be Ernest. Is this a possible answer?