Is it bad I could not cum?

I guess you were probably a bit nervous as it was the first time. Sex gets a lot better when you're really relaxed with the other person-this comes with time and experience. An hour was way too long. You should have stopped way before that, then rested maybe for half an hour then tried again when you had cooled down a bit.

It could have been anxiety, because you are inexperienced. This happens sometimes.
She knows you were inexperienced ( doesn't she? ), so, next time you should just relax better and not try so hard. Don't worry, it will happen.

Well usually it's the opposite that's the problem the first time but as long as you can cum ok when you masturbate it's isn't a serious problem. If you had ejaculated before you had sex it could be a reason as some guys can take quite a while before they cum again. I'd say just try to relax and go with the flow concentrate on the act and the sensations your feeling or maybe run some fantasies through your mind while you have sex. If you continue not to cum or can't ejaculate while masturbating and it's worrying you then see a doctor who should be able to put your mind at rest.

By the way if you can stay hard for an hour without cumming have you considered a career in the adult entertainment industry :-)