As a woman I can say that for a long, long time I was never able to cum during just sex. But, of course eventually I did. Sometimes it was because I was unsure of myself, you know a little too reserved during sex. Other times the sex just sucked. It may not be about you at all. Some women just don't have even close to an "easy O." She may just need to be more relaxed and comfortable with sex. I know that I can't orgasm when I feel uptight about myself or am concentrating too much on cumming itself. But if you know how to masterbate to orgasm, it helps make you more familiar with your body and what turns you on, and you can incoporate those methods when having sex.

yeah im w/ Tekniks even tho there is a long thread of posts around here somewhere debating on if cumming and having an orgasm is the same thing. i say yes that "cumming" is just kind of slang.
another person argued that cumming was when a woman had a female ejaculation.
on average i dont think women have as many of those as they do regular orgasms.
either way if she is climaxing and getting off then what is she worried about?
if she isn't then she hasn't orgasmed nor cummed. both of which feel very good and can't be mistaken.
hope this helps.
:P

cumming is an orgasm AFAIK...maybe she doesn't know waht an orgasm is? try oral sex and clit stimulation.. gspot too. Normally that's easier for girls.. not saiyng if they orgasm with intercourse they arnt normal, but on average.

Drew