Everyone is responsible for their own cum. She should know how to get herself off. Stop trying to give her anything. If the only thing that matters in sex is orgasm, then there is no reason to be with a person. Masterbation would take of that, and in less time.
The point of sex, in a relationships, is to share that intimacy and closeness. Great communication is needed and the atmosphere has to be relaxed.
In the past, I had trouble coming to orgasm, and a lot of that was in my head becuase by myself, I am just fine. One girl, at one point would mount me and go to town making herself cum. Another girl would rub her clit during penatration to cum. Girls hate it when you ask, "Did you cum?" That puts the pressure on them.
The point being, dont put it all on yourself as your job to make her cum. That is arraogant thinking that will only cause performance anxiety. In your case, you didnt even get it up!! Learn to share in each others pleasure and the cums will come.