In my writing class, we just read a short story that ended with two characters making out in midair. Plot aside, some people took issue with it. Why were they in midair? Why didn't they care more that they were floating? What prompted the floating? What prompted the kissing, and the touching, and the feeling?
My teacher had a gem of an explanation:
"If you're gonna float, you might as well make out."
I have to agree. I think this quote lends itself more to writing advice than one might think. It ties into non-realistic fiction more so than literary fiction, though. Despite the tireless care a writer must take in making every word, every comma, every gesture count towards the story, sometimes it's just fun to think about a heavy make out session in midair.
There are so many bits of fiction that, while not exactly imperative to the story, add to the fun and feeling. Was most of the Quidditch in Harry Potter imperative to Rowling's overall narrative? No. But it was hella fun, and it dragged us further into her world. Was it really important for Collins to describe the endless clothes and dresses Cinna forced Kat into in The Hunger Games? Absolutely not, but it DID help, in some non-official way.
I don't think this will be in a lot of writing manuals, I think, but sometimes it's completely called for to have a scene in which your characters float and make out at the same time. Or something like it.