Cannot remeber/find the title

[MessierObject]

I am looking for a story I read some time ago. It's about a couple on vacation, in Italy I think but am not 100%. They go for a walk and find a kind of magic portal on a hill. While in this magic area anything they imagine comes true, so it has threesome, enhancement, etc. For example, the husband imagines the wife with larger breasts, and the wife imagines the husband with a larger penis, imagining a third person, that kind of thing. If I remember correctly, they come back a second night, all a one part story. I have searched for hours to no avail. Any help is appreciated!