If you ask any girl, most of them will say they have never orgasmed from sex, it seems that only a few gifted or knowledgeable guys have managed it. Truth is and I hope the ladies agree with me here, its all about positioning.
Guys don't realize that the actual "orgasm zone" is the TOP INSIDE WALL of the vagina. This is
where the g spot, the deep spot, and all other sensitive orgasm zones are
located! When you are having sex in most positions your penis is going IN to
her not UP AND IN where it will have a greater chance of giving her an orgasm.
When your girl is on top of you this is what she is doing, she is leaning back so that your penis hits the front wall of her vagina. The irritating thing is she will never tell you this is what she is doing.
What you want to do is when you are entering her from behind on the bed you want to flatten her out. But, before you flatten her out you want to stick a pillow under the lower part of her stomach. Once you have pillow under her stomach (to raise her butt higher) you want to lie down fully flat on top of her.
However instead of staying even with her body, move up as high as you can. The goal of this is so that as you thrust you are hitting the top inside wall of her vagina. The entire point of the pillow and moving up on her is so that you are thrusting down DIRECTLY into her "orgasm zone." As long as you can last at least 5 minutes in this position you are almost sure to give her an orgasm
Girls tell me if you think this is all wrong :)