Partner sex is an existential experience of human connection and not a party aimed at making people come. Since she enjoys sex with you, she does get to experience the human connection and is therefore being perfectly fine. The sooner you stop pressuring her into doing ANYTHING (including having an orgasm - what a ridiculous idea to press somebody into having an orgasm against her will - an oxymoron), the sooner she just might orgasm on her own, eventually. Just stop talking about it and start to simply, purely enjoy each other's company.

Also, when you tell her that she is missing out, you are defining the experience of sex for her. You should not do that - she can define the experience for herself, and will probably revise her definition many times as she goes through life, but you should not do that for her.

Agree with Spockette, also.