Have you ever noticed that when you're writing a story in which an event occurs more than once, you describe the event at first appearance in the greatest detail, and only summarily thereafter? For instance, if a job is an important element, the first day's routine is laid out, and after that, only that part of the daily grind that supports the story is referenced. For the most part, this really helps the story move along and saves it from becoming boring.
However, there is an unintended consequence. Whatever is written about in this fashion becomes less meaningful over the course of the story. Perhaps it doesn't matter when the story is not about the diminished item. If your story is about sex, however, and first you describe kissing close up, but any mention of kissing thereafter is hurried over, then kissing stops being all tingly and exciting as the reader goes along.
This sets up a predictable trend. Sex stories tend to begin with kissing and petting episodes, progress to oral interactions, slide into full intercourse, and then move on to something more daring, such as unusual positions, anal sex, threesome sex or sex with a lesbian partner, and so forth. Sex by the end of the story consists of jumping full bore into something wild and kinky just to arouse at all. Sex stories written using this basic plot progression, as so very many do, begin to make sex fantasy within the mind itself, at least to the extent it is sparked by reading erotic literature, become increasingly boring, and perhaps abandoned all together.
What if instead of getting ever more shocking and athletic, the described sex became an exploration of the typical types of sexual activities real people engage in, and how that varies over time? Let's take kissing. There are so many kinds of kisses, even just between lovers. There are so many differing thoughts that run through the mind while kissing. There are so many physical sensations associated with kissing. Why not spend more time developing the kiss, instead of jumping to the tired old formula of ever escalating tricks?
At least part, if not most, of the reasons for the high failure rate of relationships are unreasonably high expectations that no partner can ever fulfill. Everything is so hyped beyond reality in our culture. Not every sexual interlude is going to rock your socks off. However, each one can be deeply, profoundly meaningful. It all depends on what you focus on. Our stories can be like that, too.
I mean, how many ways are there to kiss?