I'm 28 and going out clean shaven can sometimes even see me getting I.D'd!
I have how in alot of guides it says "SHAVE!" like it's the be all and end all. Most girls i've met have said they like the whole 'stubble, muscles' thing i have going. Gives a sort of gruff look that in turn makes a girl feel even safer around me, like i can somehow protect her better with stubble?!
Anyways, it's stubble all the time for me when i go out. If this girl met you when you had stubble then she might be suprised how young you look without it but that's her problem.