So how similar is the female sexual response to the male? For some guys, it may be surprising to find out just how similar we are to the woman in our life in spite of how we often look very differently at sex. Yes, there is an emotional overlay to making love for a woman that is generally not there for guys. But underneath we not as different as it might first appear.
For example, researchers found that NOS, the enzyme that Viagra acts upon, was present in various critical regions of the clitoris.  Furthermore, it was found that clitoral erections occurred through "nitric oxide and cGMP-stimulated activation of BKCa channels."  The significance? This is the same basic pathway for a penile erection. Clitoral blood flow and smooth muscle response is considered critical by researchers to the female sexual response. 
I discuss, for example, some of these similarities in my discussion on the G-Spot, where I mention how researchers have found that female genitalia has abundant erectile tissues similar to a male. I elaborate on this even further in my link on Females and Viagra, where science has shown that in many cases, females sexuality and be enhanced using the standard blockbuster PDE5 inhibitors that have taken the male world by storm.
Furthermore, almost all of the risk factors for female sexual dysfunction, high blood pressure, endothelial dysfunction, cardiovascular disease, being overweight, etc., are also risk factors for us guys as well.
And I have already shown how females are very much visually stimulated as well. In other words, Looks and Appearance Are Very Important to Females as well.
So what does all this mean? If you can understand and satisy the emotional component of the woman in your life, then underneath you are not facing the Unsolvable Mystery. Underneath it all, she is remarkably similar to you in many key ways.
REFERENCES:Oxide Synthase Isoforms in Human Clitoris"
2) The FASEB Journal, 2004, 18:1382-1391, "The neurovascular mechanism of clitoral erection: nitric oxide and cGMP-stimulated activation of BKCa channels
3) International journal of impotence research, 2001, 13(2):116-124, "Decreased circulating levels of estrogen alter vaginal and clitoral blood flow and structure in the rabbit"