I've been this girlfriend and it's not long gone. I totally feel with her about that degraded feel about blowjobs. I didn't even wanted to touch my bfs penis the first months and after a while of penis touching and having sex he told me he would like to get a blowjob and asked what i thought about that. I didn't really thought that it was an option for me. Because I thought that's what whores do and i also thought it is disgusting. Well, what helped me getting over that, was months of just having sex and cuddling, just giving a lot of love to me, until I trusted him enough to give it a try without the feeling that he would laugh at me if i'm not doing it right. Besides I just started with a little kiss on his penis to see that it won't bite me ;D And a real blowjob came like a month later after many kisses and like cuddling with his penis.
So if your relationship or her sex life is relatively new, you should just give her time. I really needed a long time and you should just talk a lot and having fun and some day she would maybe give it a try if you swear that you won't cum in her mouth (was very important for me and still is). Besides: She knows you want a blowjob, you told her I think often enough, don't ask for it all the time. She will say or just do it if she feels ready, but if you tell her all the time, it's just a lot of pressure. Just don't push her and if she does it just tell her how good it feels and after a while of her exploring it by herself you can start on giving tips or maybe she will ask for some. I personally still don't love giving blowjobs but at some days I just feel I'm okay with it and I would like to see how he likes it so I just go with it, not really often, like once in a week or less but he is okay with that and you should be prepared for her for maybe just don't like it and you should be okay with that. And never ever be like "I went down on you, so now it's your turn to go down on me" It's just stupid. My bf loves to go down on me even i'm not returning the favor. That's just my opinion and kind of my story, Sorry it got so long and sorry for every mistake, spelling, grammar (not my native language).