It's generally considered a nice thing when the walls come down in a relationship. But not literally. And not when it comes to the bathroom.
You won't find open-plan bedroom-bathroom layouts in traditional, long-standing hotels, but for newer, edgier establishments, it has become something of a trend.
Whether that be a complete lack of partition between sleeping and bathing quarters, glass walls, or loos without doors, you can wave goodbye to your washroom privacy upon check-in - and who wants to do that?
Traveller.com.au's review of the Miss Clara hotel in Stockholm, for example, mentions: "At night when using the bathroom light it's easy to see in. You'd best be very comfortable with anyone you're sharing the room with."
"I guess it could be sort of mysterious and sexy in the right circumstances, but it's definitely only awkward when you're sharing the room with your dad," a guest at the Hôtel Le Germain in Toronto once told The New York Times, regarding the glass window that divided their room from the shower.
I can relate, having recently stayed with my father at a hotel in Cape Town, in a large (and beautiful) suite with an entirely open-plan bedroom-bathroom layout, and twin showers without curtains. The beds were separate, obviously, but when it came to shower time, one person was always banished to reception to sit in idle wait.
As for couples, some appear to have no issue taking their open-door policy away with them on holiday, while others find the prospect horrific.
Take the Sentido Aegean Pearl, a five-star hotel in Greece in which some of the en-suite bathrooms are open-plan. Comb through the (mostly very positive) TripAdvisor reviews and you'll find plenty of mentions to this.
"Okay for close couples so wasn't an issue for us but there was a severe lack of privacy," one noted, while another simply said the layout caused "much amusement".
Others didn't quite see the funny side. "I don't really understand why this room design exists - surely no one would want a bathroom to be like that?" one guest commented. "The design is mad and made this unsuitable for me and my teenage daughter," another complained.
Similarly, a review of the Blue Woods Hotel in Belgium, warns: "The open-plan concept extended not only to the glass-walled bathroom (OK by us) but also to the loo, only partially concealed behind a wall in a door-less alcove. Some things are best kept private."
A TripAdvisor review of the INNSIDE Manchester hotel reads: "If you need the loo in the middle of the night, there is no way of turning on the light without waking the other person as the open-plan bathroom is right next to the bed with no partition wall. Not good if you're at all anxious about privacy on the loo either."
And it's not just boutique hotels. One guest from the Waldorf Hilton in London declared the open-plan shower and toilet arrangement to be "an absolute disaster".
So why are hotels designing their rooms this way?
"Today's generation are more comfortable with being exposed, hence this growing phenomenon," states Drench, an interiors supplier.
"The lack of dividing walls means that natural lighting can fill the room and the panoramic views can be fully appreciated. If well-designed, the close proximity can make the bedroom-bathroom areas feel much more spacious than they actually are."
Some hotels have embraced the trend, but taken steps to regain some level of privacy as part of the design. The Hotel City Lugano in Switzerland, for example, has rooms with bathrooms right by the bed, encased in glass. Initially a horrendous prospect, but fear not - there is a curtain you can pull over one wall.
China's Renaissance Beijing Capital Hotel, too, has in-room bathrooms with completely clear glass walls, but you do have the option of a "privacy blind".
And while we're on the topic of confounding bathroom design...
What's with those telephones installed right next to the loo?
This, it seems, is a hangover from the times before cordless phones. Industry experts took to question forum Quora to clear things up, and most agreed it was essentially a status symbol.
"Having a phone in the bathroom was considered an amenity, a mark of luxury," a user wrote.
"They were installed for the convenience of guests who needed to receive calls in their rooms, and who might be in the bathroom when those calls came in."
Back in the day, it also used to be a requirement for hotels vying for a better AAA rating. Until 2008, access to a landline in the bathroom was essential in order to achieve Four or Five Diamond status. For many older hotels, they remain for this reason.
The Telegraph, London