It Started As a Fantasy

BOYFRIEND and GIRLFRIEND are not hyphenated! Only skimmed this to see if it was the same as the description, it was, no score!

Wrong category - no wives here.

And it wasn't a well done erotic story either.

@Wrong Category

If you, like so many anons and others here, plan on being category police at least know this:

From the MODS: Cheating girlfriends, fiances etc are OK in the LW category! If you have an issue past that point take it up with the site owners. Stop showing your ignorance!

For me stayed a fantasy...

For me stayed a fantasy...3*

Not a bad effort. Wasn't badly written, but a bit on the saccharin side. At least for me. Keep writing.

Reverse cuck story? Stupid man, or stupid woman, still really stupid idea.

So you think switching the genders makes this original? What might be original is describing a flaming queen and finessing that past the readers. Purple shirt, purple scarf, Italian shoes? Who the fuck knows where shoes come from by looking at some queers feet? Only another queer. "Oh my God, Italian shoes, fuckme fuckme fuckme!" Its the purple scarf that really sets the clits and the cocks throbbing. Actually that's pretty funny. Thanks for the joke.

Right....girlfriend sets this up as exciting and completely innocent....

....right. While he's shagging the 40-something MILF, girlyfriend is off shagging MILFs hubby or a new flame.
OK, no more sarcasm.
From the overt and extensive use of past-perfect and present-perfect tenses, I take it you are of Indian background. Nobody else writes or speaks like that. It is a characteristic of folks whose primary language is Hindi or a relative dialect.
If you want to mask that, you might study writings by British and American authors, paying very, very close attention to how they structure sentences.
Not a bad story, if one can get past the intrinsic and roaring trust issue created by a spouse or girlfriend/boyfriend raising sharing during sex.

Grammar

And while we're being the Grammar Police, there are no spaces in contractions!

It's "don't" NOT "don ' t"!

Interesting

Note: "in same building that her girl-friend had booked"; 'seine Freundin' is his girlfriend. (I read both versions)