Haha, and this feels like the answer I give every girl, not because I think it's their problem, but because I think it's a very unknown aspect of female arousal and orgasm that has shown to be true, and I'd hate for someone never to find the missing piece to the puzzle.
Histamine levels play a role in your arousal and ability to achieve orgasm. High levels make it easy, low levels make it hard. Same for men. L-Histidine, an amino acid would increase it, L-Methionine would decrease it.
You can talk to your doctor about your concerns and if you're curious about what I mention, you can have your Histamine levels checked.
-Histidine is involved in the function of the thalamus and hypothalamus glands, and orgasm is triggered when histamine is released from the mast cells in the genitals. Histamine also causes the sexual flush that occurs during arousal. Many women fail to achieve sexual pleasure and orgasm, and often other treatments including psychotherapy may be unsuccessful. This problem may be a result of a biochemical imbalance, since sufficient histamine must be present in order to trigger an orgasm. Deficiencies of L-Histidine will effect histamine levels.
-Supplementing with L-Histidine will increase histamine levels as proved by Carl Pfeiffer, M.D., and Ph.D. in his research on non-orgasmic women. He administered doses of 500mg. of L-Histidine (1) before each meal (for a total of 3 per day) restoring sexual pleasure in women. (He also helped women who had irregular periods become regular by giving doses of 4g. per day).