Getting rejected by women is part of being a man. And yeah, it can hurt, but calling her a “bitch” for politely declining a date offer is… well… being a bitch. (It’s also a big reason most people choose to just ghost each other instead). Remember that finding a date, like finding a job or anything in life, is a numbers game. Take the rejection in stride, wish her well, then get back out there and shoot your shot with one of the millions of other dating options. I guarantee that if you ask around enough — and possibly recalibrate your standards looks-wise — you will eventually find someone who sees how awesome you are. That’s the kind of person you deserve to be with, after all.
Also, if she rejects you or reveals that she has a boyfriend and you respond politely, then who knows? Maybe she has a friend for you. Maybe she’ll think of you when she and her boyfriend break up (but don’t constantly ask if she’s single yet). Or maybe she’ll find your polite response so refreshing and unexpected, she’ll change her mind and accept that date after all.