OK, SB #1 was a gorgeous blond 22yo who said she did not do oral. But after we dated for a couple months and she came to trust me she told me why. Turns out every single guy she had been with before me was a total asshole who would grab her head and choke her and make her gag. So she thought that's what oral sex was always gonna be like. No wonder she wouldn't do it. I told her I was shocked they would treat her that way and I never would. She proceeded to suck my cock very sweetly nearly every time we dated after that!
SB #2 was a tall skinny alternative style girl, very open minded in most ways, but refused to give oral. She loved receiving oral from me, as did #1, and I love eating pussy! Never got her to change her mind, but continued dating her for a very long time because I just liked her a lot and doing without a blow job simply was not a deal breaker with me.
SB #3 is a newbie in every way. Only 19yo. I'm the first guy from SA she's been willing to meet irl, and the first she has fucked. Turns out I'm only the 3rd guy she's had sex with ever, so she's practically an innocent virgin! This was just 3 days ago and I plan to see her again next week. She's so inexperienced that when I was fucking her in mish and I asked her if she liked being on her knees, she said I don't know I've never done that! Well she certainly has done that now! Anyway, this girl will not participate in oral, either giving or receiving, which I find odd. But give me time, I think my mission with her is to expand her sexual repertoire.
The great majority of the girls I've dated love sucking cock and some are actually very good at it. So yeah, it's kinda off- putting when a girl says no to oral. But work with her for a while and you might be able to change her mind.