I too, do not believe that she has feelings for you.
Also, I think workplace romance may not be a good idea for anyone. It can get messy and more trouble than it is worth.
Sending your boss flowers is not a good idea.
Flirting in the workplace is not a good idea.
People smile all the time – it does not mean they want to hook up with you.
Boss might favor the guy because she feels he is better qualified.
Move on, and keep it outside the workplace.