A man is shrunk by a gorgeous couple, and used for their pleasure. 

The good version is here (with illustrations!):  https://www.deviantart.com/sgrildrig/art/Threshold-Tours-954807282

This is a macrofur story.  Sapphire and Loey discover a tour that promises a simulated visit to another world.  They get more than they expected.  The touring company gets more than they expected.  And the place they visit gets way more than it expected.  There is humor.  There is smut.  There is destruction.  There is gelato.

Maya Krungthep and Chloe Moore were the best roommates one could ask for, having lived together through two consecutive years of college. However, when Chloe developed a rare condition that caused her to nearly triple in size, she became a recluse who seldom leaves their room. Now, as Maya succumbs to the irritation of living with Chloe, will the moody minigiantess take out her frustrations on her smaller roommate as well?

A team of Peacekeepers can easily dispatch an army of humans. But the task isn't nearly as easy for a single Valkyrie.

Your girlfriend kept you after you shrunk, though unfortunately discovered your cache of giantess stories.

Surprisingly she loved them, though the cost of you keeping her entertained may be too much to handle.

Aaron, a smaller than average runt, meets Tifany on a flight home. Their size difference is of mutual interest, and they get to know each other better. They share an instant bond, and the fact that Tifany is slowly growing larger and Aaron is slowly shrinking and getting thinner seems to only encourage them both.

Derek's attending the big game to support his girlfriend and her fellow cheerleaders. He quickly learns that it isn't wise to mix alcohol and a girl who can change size at will! Hopefully he can put a stop to the whole thing before it gets out of hand...

A willing tiny prey. A woman who needs the energy. Nobody around. What could get in the way?

...A laundry list of medical conditions that make Riley's descent into Emmeline a real tight squeeze!

(Warning for scenes of asphyxiation)