Cumming in mouth
My girlfriend and I have a healthy sex life, but we also have quite different experience levels and views on sex. I say this without judgement, it would be fair to label her tastes as vanilla. For example, she will still say to me I'm being "gross" if I try and flirt with her and say something like "I really wanna eat your pussy" or "I can't wait to fuck you when I get back" if I'm away for work. She desires me, she just gets embarrassed by that sort of language. She has had less sexual partners before we met so this may be a factor. We're both in our 30s. None of this is an issue really, I just want to give some context to my dilemma.
We've been together a few years now and over that time have compromised with each other. For example, in the beginning she said she didn't like giving blowjobs, ever. I made sure I didn't pressure her, however over time I explained why I enjoyed it and I found not asking for it made her feel comfortable to eventually incorporate it into our sex life. It also helps that I enjoy eating her out so it's reciprocal.
The line for her, though, seems to be me cumming in her mouth after giving me a blowjob. It's not a case of spit or swallow, it's neither. Of course consent is crucial and as I have for previous things in the bedroom, I don't want to pressure or 'convince' her to do things just because I want them. I don't think this is something she will change her mind on over time. What happens at the moment is when I'm about to cum I tell her and she takes my dick out of her mouth and finishes me with her hand. I'm not sure if anyone can relate, but this kind of kills my orgasm, it ruins the intensity and it's just not the same. I really appreciate my girlfriend giving me oral sex though and I don't want to say anything to discourage her. I've mentioned cumming in her mouth occasionally but she's not interested, for now at least.
Is there anything I could do to make her feel comfortable with this? Or do I need to just enjoy what we have? I'd value anyone's insights and advice.