i am going to make a guess and say that she is using a computer that you have access to. if that is the case than you could get a keylogger and keep track that way.
in case you dont know a keylogger is a program that runs in that background and is pretty much invisible to the users. you can set them to as you probably could guess log whats typed some even can take screen shots every X mins, sec what ever you want. i think that would be the best thing to do in your case.
hope that helped and i hope everything works out.