Hey
Hentai_Kishi I just read Winter Friends, from your master page (where you said you hadn't found a free version, and hadn't read it).
Here's a review if you feel like updating or following up on it:
Really good wholesome swinging, albeit in novella format. It's like 79 pages or something, with a rather well developed fantasy world. The initial premise is that they live in a harsh northern climate, but the 'gods' give equal chances by several drugs lol. There are at least two type of mushrooms/plants that straight up induce various states of mind. The MC's past, he survived using a Berserker drug (Norse influence for sure here) against a huge army of monsters. His childhood friend (male) returns with a wife from years of adventuring in the south (freer attitudes; his wife is... aggressively sexual, and he loves it).
Won't spoil anything further, but there's actually some decent worldbuilding, more than I'd expect from a erotic novella. The pair of couples use a second type of drug, that basically is 'higher state of mind' that is stereotypical of shrooms(?) (Don't know, I don't nor have ever done drugs). Anyway, it's a very wholesome trip, and they liken whatever happens under its influence to be the will of the gods. Cue orgy. That, over the months, leads to eventual swinging.
Basically the only downside of the novella is based upon the inherent state of being a novella: it's too short. There's only one scene of swinging (but it's a good 25% of the book).
All-in-all, I was quite impressed by how much went into the book though; not what I'd expect for an erotic 'short story'. Good worldbuilding, no NTR or any of that, hot sex, etc.
Worth a try if you like swinging. There's very little netorase content other than the implicitly stated parts in the swinging scene, but it covers a variety of poses, acts, MFF, MMF, FF, MF/MF, etc (no Male on Male for those who are worried). It's honestly a great scene, even though there's only one.
Note that it's on Kindle Unlimited, so if you have a membership (or pick up a free trial) you can read it for free. Otherwise, $2.99 (well, in the US at least).