The common mode of sexual intercourse is not even natural. Our genitals are not for pleasure, they are for procreation, and that occurs when two people are very much in love and wanting to reproduce. Nature takes its course when the couple are asleep laying naked and embraced. Procreation occurs by the vagina acting as a vacuum, drawing the flaccid penis inside to a climax and eventually, ejaculation.
The vagina then releases the penis, all the while not disturbing the peacefully sleeping couple.
Forceful sexual intercourse is unnatural.
Apparently, this is not the belief of only one crazy person. It started with William Chidley in the mid-1800s (note, this article also discusses Walter Balls-Headly, whose views seem apt with his name....).
Chidley developed the theory that there was something profoundly wrong with the way in which modern people had sex. The introduction of an erect penis into a vagina, he said, was unnatural and produced shocks to both men and women that led to their physical and mental deterioration.
Sex, claimed Chidley, should only occur in the spring, when the vagina would act as a vacuum and so draw the flaccid penis inside.
But, though maybe a bit crazy and lacking understand, Chidley wasn’t bad. Some of his theory was rooted in the idea that sex should be better for women.
In the current unnatural mode of coition, he added, “some people – especially women... always suffer: their married lives are one long suffering.”
“The womb and vagina of a beautiful and healthy woman, believe me, is a living, vital, moving organ, sensitive to a look, a word, a thought, or a hand on the waist: but as we have coition now, a woman and her womb might as well be dead.”
The whole article is a long, but interesting read (at least my skim of it was....because as mentioned, it’s long)