Board Thread:Questions and Answers/@comment-186.214.54.139-20140109005031/@comment-3250527-20140109010459

I believe Asuna means the memories of when she first entered SAO. If you read the Progressive Light Novel Series, Asuna was actually immensely scared of being trapped within the Death Game, and then resolved to training all day and all night in hopes of clearing the game or die trying.

Otherwise, she had reprimanded Kirito (in the LN and in the anime) for doubting that their love was real or not. Also, when speaking to Nishida, Asuna said that she was not angry or sorrowed by the memories of SAO (rather than losing a day of reality, gained a day in the VR).

So, I believe Asuna was referring to losing everything that was meaningful to her because of a game or separation thus.