While this is an old thread, it's undoubtedly a recurring matter.
Matthew, how long have you been training? I only ask because you owe it to yourself to develop, which will benefit the development of everyone in the dojo, including this be-witching specimen you speak of. For one, you'll be that much more irresistible once you've hit 4th Kyu. Nothing says Hot-Stuff like nikyo-induced-slapping-of-the-mat.
In all seriousness, there is nothing to be ashamed of. Perfectly natural. At this point it time you find value in aikido. Look, a gal who also values aikido. You share at least one interest, and perhaps for you at this point in your training it is quite a consuming interest.
As far as I know the only aikido etiquette that applies is to separate your natural and acceptable interest in this person from your interest in training, and your interest in the safe, enriching, life-long friend forming practice with everyone you meet, including your crush.
At this time you no doubt want the best for her, but right now all you can bet on is her interest in aikido. Support her interest as everyone else in the dojo are doing already, first as a wholly present individual, and eventually as a compatriot. Over the time that may take, you'll have a more realistic impression of yourself and of her, and you won't regret having taken your time if
things do in fact start to click.
So re-direct your infatuation into working 20 minutes after class on ukemi. Hit the gym. Take voice lessons. Pick up gardening. Swing-dancing, whatever, ...