Others identify as butch or stud, but like the sexual relationship to be reciprocal. Since your partner is talking to you about performing oral sex on her, my guess is that she’s not stone.
What do I think you should do if she asks you again? I think you should talk to her about your feelings. I’m speculating about why you don’t want to have oral sex with her? Is it the stone dynamic I just mentioned? Is there something else that makes you uncomfortable?
Some people do not like to give or receive oral sex, but because you say you’ve done it with other partners, I don’t think that is your issue. Remember the best way to have a satisfying sexual relationship is to be able to communicate--about what you like and what you don’t like. About what turns you on and what makes you uncomfortable.
So before you start heading toward her southern lips, move your other lips--talk!
If you do decide to give it a go, here are some Tips for Better Oral Sex.