Alright man, you obviously like the botony girl more than other one. So, here's ya do. 1. Don't announce to the botony chick that you're taken. 2. Work on your game with her, and when you think you got it, get her number and take her out. 3. Go ahead and roll along with the other one until things get going with the botony chick.
And ya, just cuz she has a boyfriend does not mean that she is out of reach. It's not too tough to get a girl away from her boyfriend provided she doesn't love him. All you have to do is be better than her boyfriend. If she is in fact attracted to you (and it sounds like she is going off of what you provided) you shouldn't have too much trouble. Assuming you know what you're doing...
Good luck man.:thumbsup: