What do you mean I need her to send me an invitational letter. And what is that?

Brian, if you can get an invitation letter from her, then you don't need to show round-way tickets and hotel reservations when you apply for the Chinese visa. The invitation is an letter from your fiance, which includes your particulars as well as your fiance's and information about your trip to China, such as stay length, places to be visited, etc. The letter can be a printed or scanned copy or the original copy.