There are no tips anyone can give you on this.
You're going to have to take your chances and be prepared for being shot down.
I'd say if she's never dropped any sort of a direct hint at you that she has an inkling of interest, then she's not interested enough to upend her relationship apple cart with her boyfriend for you. You'd know by now if you had a chance with her.
People treat you the way they feel about you
If you choose to remain with someone who doesn't treat you well, you cease being the victim and become the volunteer.
~Derrick Jaxn -- look him up