Some couples don’t want or plan to have children together, though, and yet they stay together. That’s because there’s another facet to sex besides procreation and pleasure, which I think is even more important than either of these. We long for closeness with another person, and we want that other person to allow us to be that close to them.
Every human ultimately wants to be and feel accepted by another. The ultimate acceptance is to agree to join your body (and deeper parts as well) together with another person’s through the sexual act. When you have sex with someone, you say in a physical (and deeper) way, “I accept you.”
(This is true especially for females, who actually invite their partner into their bodies.)
Our genitals are very near our center of mass, the tanden in Japanese, which is located just below our belly buttons. A woman’s uterus is her body’s center of gravity. Maybe that’s why she typically feels a deeper connection than the man does when she has sex: the male literally touches the center of her.
There’s a reason why our genitals aren’t on our heads, or buttocks, or feet. When a man and woman copulate in the missionary position (or its variants), their tandens are pressed together. Their bodies are as close as they can be, and they share the same center of mass.
They are as close to being a single body as humans can get.
In this position, their bodies are mirrors of each other: eyes to eyes, mouth to mouth, pelvis to pelvis. This closeness (physical intimacy) is why our genitals are near our tandens, and it’s one reason why we desire other-sex companionship, even briefly.
It’s also why neither males nor females can have this same level and kind of intimacy with a same-sex partner. Other sexual positions and acts are less intimate than the male-female (vaginal) missionary position, and other bodily configurations don’t offer the same potential for physical—and thus emotional—closeness.
A true other-sex companion isn’t only an intimate sexual partner. The mate we seek also has some of the qualities of our same-sex friends: we share many of the same thoughts, feelings, interests, and activities. Sexual intimacy isn’t enough to have a fulfilling mate if we don’t share the rest, too.
Of course, it’s still important for both males and females to have same-sex companions. With them, we can share a mental and emotional connection that can be hard to find in the other sex. But having a partner who connects with you in other ways, too, is one of life’s great joys.
(Written in 2005 and freshly edited on December 19, 2016.)