AITAH for asking for a blowjob from my girlfriend

My girlfriend 22F of 7 months has never given me a blowjob and I don’t feel right asking for it. I 24M was her first time ever, even her first kiss. So I have been really patient and consensual the whole time. Sex is great, we both cum almost every time, and we can last anywhere from 30 minutes to 2 hours so I feel like I am really putting in the work to satisfy her the best I can. She is very happy as things are. I have offered oral on many occasions and she just says “no” and sometimes says “ew no” and is grossed out about the whole thing in general. I was once in a threesome so I know what sucking dick is like and it was way easier than I expected and honestly fun. As long as it’s clean and shaved I don’t see the issue. I don’t even need to cum in the mouth if she does not want that. She is WIFEY material and super respectable person all around. So maybe this is why she is just not cut out for this. I used to date “sluts” for lack of a better term and BJs where just automatic but so was all the cons with hyper sexual people like cheating, going out to raves wearing stickers instead of clothes, twerking on people, etc. I finally found a girl I respect and want to marry. This is literally the only “issue” and it’s not a deal breaker. How would I ask her? Should I ask her?