Fetishes that aren't fetishes

So a few months ago I read this story. As implied by the blog title, it was in fact a sexual story, shock of all shocks. Within it,the second person Main character falls in love with Braeburn and I presume they have sex. I say presume because I had to stop reading it about halfway through.
[Side rant, people are making their first/second person original characters way too detailed for me. Don't tell me that I lived in Texas and went to college for writing. I didn't.]
So in this story, (the name of which escapes me) the main character struggles with a homophobic upbringing and homosexual feelings for Braeburn. It is really well written. After a massage scene [GONE SEXUAL] They head into a barn for some rumpy pumpy. I usually dislike sex scenes because they use weird terminology and the descriptions make everything seem kind of gross. But I was happily expectant for this story, because it was really well written and thought provoking to that point.
So they're kissing, cuddling and canoodling, and they start stripping. They're both fully nekkid, when, as the tension builds...
Main character puts on Braeburn's vest. Brae puts on Main character's clothes, and all tension, sexual or otherwise is lost. They start doing the biz, but it's just not sexy. I stopped there.

Why are there so many things in sexual stories that just aren't sexual. Like, I get most fetishes. I see how they're sexual, but doing a bad impression of your partner isn't sexy, it's dumb.

Also, why7 are there so many words that are commonly used that are bad? "Slit?" "rod?" "Member?" What the fuck?