The good news is that characters have sex. The bad news is that sometimes you have to get them to that point, go through the whole event, and figure out (as in life) how to negotiate the post coital landscape. Will they ever see each other again? Do they like each other? What's going to happen to their relationship now?
And worse,how to write the things that are of the body, internal, visceral feelings in English? How to label the body parts and the actions and bodily fluids no one really likes to talk about anyway, except with a girlfriend and even then, sometimes you get the, "Wow, that was TMI!"
I have read some sex scenes that have made me want to spit up my morning orange juice. I mean, the terms some writers give to body parts boggles my imagination. I think the worst was "silken purse." Are we in the Victorian era? Vagina is a difficult word to use except at the gynecologist office, but silken purse? And let's not get started on the male member. Penis is really very clinical as well, and it isn't a word people often articulate in the throes of passion. But man pole? Or throbbing "whatever" is pretty ridiculous as well.
So here's my take. You don't have to label any of those terms. You don't have to describe the stages of arousal and orgasm to convey sex fully and wonderfully had. You just write about the body. What does this coupling, this touch, this person, this feeling "feel" like inside. In the chest and heart and belly. What does the air around the skin feel like? What are the thoughts in the mind, the colors, the memories that come to the characters?
The movement is in the act of touching and being with another person, not the blow by blow (no pun intended) of the act itself. Yes, there is usually a goal to lovemaking in a literal sense, but there is this symbolic union, the bringing together (even if it is for a short and solo time) of two people. What does that represent to the relationship, to the narrative, to the story.
I talked about this with my class yesterday at UCLA (a wonderful class, wonderful students), and I think that all sex scenes need to forward the theme of the story, the development o the characters, the arc of the plot. There is a purpose for the sex, not just a need to put a sex scene into the story because it's page 45.
My favorite book on this topic is: The Joy of Writing Sex: A Guide for Fiction Writers: Elizabeth Benedict. she pretty much says what I am trying to say above but with much more detail and eloquence and meaning, too.
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