I'm sure you aren't Peter North ad I'm sure she doesn't expect you to shoot like him.
Hey, if she asked then she's definitely willing. Go ahead. The more the merrier. It's natural, so it's to be expected. I'm sure if it's too much, she'll simply say so or move. Don't worry about it kid. :)
Some girls like it, I included and others don't. If your girlfriend wants you to give her a facial I don't think it matters if you shoot a lot. Just really do NOT get it into her eyes, sh*t hurts.