Okay this thread is a little borderline... but in the interests of science I'll respond to it. Maybe STella will move it, but so far doesn't look like any women-bashing posts.
Any guy who comes on here and posts about women enjoying rape in a childish way will def be deleted.
I too used to volunteer at a women's center, and the statistics show that while some women do reach orgasm, these are NOT the majority. The reasons for it include a lengthy rape period (over several hours) where the rapist usually forces the woman to masturbate, or performs oral sex on her. (Believe it or not, some rapists do this to delude themselves into thinking it's "consentual." It's rare for orgasm to occur during a fast, penetration-only rape. The women do not bond with their rapists, and in fact, the highest suicide rate among rape victims occurs with women who have reached climax during the rape. Other reactions to the terror experienced during rape include urination and defecation.
Many women do seem to enjoy rape or domination fantasies, but there is some evidence to indicate that this is a result of the guilt/punishment women historically have been made to endure for having/enjoying sex, rather than some evolutionary holdover. There are also many men who enjoy the idea of being dominated/spanked etc... by women. (I personally would vouch for that since for some reason I seem to attract a good number of them at department stores, the post office, on the street, etc.
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As for the other, I would say it's one or a combo of reasons including lack of the partner's skills, lack of experience, inability to let go.