Here are two files from a SoundCloud user who posts as "Sex Sounds & Orgasm Moans." Most of his recordings, which date from 2014, are of him masturbating and talking dirty (he may be a Reddit user, as that's quite popular with the "Gone Wild Audio" crowd), but these two files document part of an affair he had with a woman he refers to only as "Snow," clearly not her real name. Her husband, or boyfriend, was sexually inattentive, so naturally she sought relief in the arms of Mr. Sex Sounds.
A portion of the "Snow Sex" file was apparently uploaded here as "Carnal Sex Noises" --it's on my hard drive, at any rate, so I think it came from here-- but I haven't found anything to indicate that the rest of the material was ever uploaded. My apologies if this is a repost.
Neither file is of their first encounter, but they can't have been together very long when these clips were made. The recordings seem to have been made on two different days; I believe "Fucking Snow" is the earlier one. She has a lovely voice. He engages in lots of dirty talk, partly for the benefit of the secret listener, and she responds gamely. (Happily, she also doesn't flip out later when he shows her he has made a recording.) They seem to have good chemistry. I made a couple of small edits to remove a somewhat off-topic conversation that was mostly inaudible.