Your lady really doesn't want a dozen (or two, or three) long-stemmed red roses. For reals.
I say this from my perspective as a woman, someone who's also heard this from almost every other woman I've ever asked about this, and as a former flower shop owner. Every year, my female customers would tell me some version of, "When my husband/bf comes in to order flowers, please steer him away from long-stemmed red roses. Please suggest something prettier!"
Sure, she'll thank you profusely, and you'll definitely get credit for getting her the traditional flowers, but if you want her to think you are the sweetest, most thoughtful bf or husband ever, have the florist make her a bouquet with old-fashioned roses, instead. Also known as garden roses, they are very different from the standard, long-stemmed florist roses, and your girl will swoon when you hand them to her!
They're tres romantique and they smell heavenly, since they haven't had the scent bred out of them, like most florists' roses.
Here's some interesting info on the history roses: