Frustrated

You say your girlfriend hasn't had an orgasm during sex. I presume you mean during intercourse.

According to statistics, more than half of all women never achieve an orgasm in intercourse. This is because the female body is designed so that it is hard for her (no pun intended) to orgasm in intercourse. The reason for this is because the contractions associated with an orgasm cause the semen to flow from the body; so as you can see, nature has arranged it so that the semen will stay where it's put.

There are things that you can do to increase the chances of her achieving an orgasm in intercourse. These include: giving her longer foreplay; combining clitoral stimulation with intercourse; and using intercourse positions that heighten stimulation to the clitoris (such as woman on top).

If she still doesn't achieve an orgasm in intercourse despite your efforts, don't worry, that's normal too. I assume that when you said that she can't have an orgasm during sex, that you didn't mean that she can't have an orgasm with you at all, no matter what type of sexual stimulation you give you (oral or manual).

If it is true that she can't come with you at all, you need to find out if she can have an orgasm by herself. If she can't, then she needs to learn how to masturbate herself to orgasm. Lonny Barbach's book, For Yourself, teaches a woman how. Once she knows what works for her, she will be able to take her show on the road, so to speak, and instruct you on what to do.