As far as I know pending requests are no longer visible in your friends list. On the
Facebook discussion boards it looks like they changed it over a year ago (to no longer list pending requests in your list of friends).
On
the friend's profile page (where the 'friend' button would have been) it will show as 'friend request sent' if it has not yet been accepted or denied.
If the request has been denied and the person marked that they do not know you there will no longer be an option to add them as a friend.
If the request has been denied without a mark against the request the 'friend' button will be visible again.
Also, to cancel a pending friend request she can navigate to the friend's profile page and scroll down to the bottom of the left column - look for the 'cancel friend request' link. Of course to do this she would need to have kept track of who she requested connections with since there is no longer that handy list of pending requests.
There is also no record that someone has deleted you from their list, or vice versa.
I hope this helps!