Saying anything would just cause drama. Just make sure your bf gets at least as much flirtatious attention from you as she give him. I'm not saying you have to text him non<x>stop, but do things that would make him remind himself that he doesn't need her because he has something better already.
I would just leave it alone, things like that tend to just fade away if you don't make an issue out of it
Is your boyfriend bisexual?