I resist the word penetration as a term to describe intercourse from a biological male perspective as it carries an invasive undertone. But the action itself is almost irresistibly desirable, not because it demonstrates any dominance attempt or desire of possession, but because of the actual physical presence of being possessed.
Being enveloped by a body, being accepted in a physical form, being hugged by the most intimate part of a human body.
It’s the only thing that a female body can not perform, or being performed, in a sexual context. But at the same time a woman become the only one who is capable of giving that acceptance, and ultimately, giving birth. In such an angle, the role of (physical) male body and female body in a sexual act is reversed, the female body being the one that is giving (compare to ejection), and the male body is the one receiving.
The Fleeting Moments 