You have a hot character or two. You have an awesome plot with a surprising and touching ending, and some absolutely sizzling sex scenes! You are nearly there in writing a story or book deserving a 5-star review, but so far, it's only a 4. Lots of your competitors' stories have sizzling hot sex scenes, believable characters, and great plots. And after a while, in my own humble opinion, these stories start sounding the same. The plot and the characters are well drawn, they hang together nicely, but something is missing. One way to push it to the top of the scale is to make it a tearjerker, but that's not my point here. I suggest that you use
all
the tools at your disposal, and be subtle when you manipulate your readers. An important tool to do this is the setting of your story.
Now setting is a bit like salt: a little goes a long way. Believe me, I've made that mistake. I speak from experience. That's why I recommend the Goldie Locks approach. You know: not too much, not too little, just... enough.
The setting in which your characters act out their erotic and romantic trysts is just as important in immersing your readers in the story as giving just the right hints of what the characters look like, and how they act. Setting is definitely a hidden character. Think about it: a guy and a girl meeting in a crowded, neon light-drenched supermarket will act just a bit differently towards each other than they might were they to meet on a winding trail, sunlight peaking through the tree canopy in the mountains. In the supermarket, even if they acknowledge each other, they might barely nod as they push their carts around the aisles. Packages of frozen peas are not sexy, and Johnson's baby oil is a bit over the top and clichéd. In the woods, soft shadows playing across their faces, they might stop and exchange some chitchat about the trail, drink some water, get to know each other in a more relaxed way.