Room divider - one-sided or double-sided?

My concern is that if I paint one side white, it will get dirty after a while because the children often touch it.

You have to worry about that in the whole house. Children constantly touch walls (stairs and doors are especially popular). But there is a solution for that: repainting ;)
I know how it is with my three kids... It's not worth thinking too much about it or getting upset.

Marble plaster could be the right thing, just need to find someone who can do it and offers a good price (supposed to be expensive)

, I know, but the frequency will be higher at that spot :-).

looks like this later (also available in other colors, is mm-thin natural stone):

:eek: Looks like our shower!

I like this detail, it gives the room spaciousness and doesn’t make you feel “boxed in.”

The separation between ceiling and wall at the top basically has something floating, transparency.., I can’t find the word, but light can continue to shine through. You know what I mean :)
The effect looks nice when there is only a narrow strip of light at the top, allowing the wall to just be a wall, with brightness coming through.
However, these posts on the left and right as well as the size ratio between wall and open space diminish the effect.
Also, the passages on the left and right give a very different impression than I thought the topic was about.
It does not have the spacious effect one would expect it to have.
But my idea doesn’t matter, it’s the wishes of the clients that count. The main thing is that you are happy...
Regarding the question: I would hang cushions on the wall as back padding for the bench.
Coat the wall with latex or wallpaper. You can easily modify or/and wash all of it.

Marble plaster could be the right thing, just need to find someone who can do it and offers a good price (supposed to be expensive)

I have seen a wall like that in the area with a "leather wallpaper," I think that's what it's called; looks fancy.

Addendum: I wouldn't emphasize the wall. With paint or anything like that. Somehow the various horizontal lines in the room seem a bit too much to me. The kitchen is doubly emphasized, the video area has a different height... the TV also draws its line...

Addendum: I wouldn’t emphasize the wall. With paint or something. Somehow the various horizontal lines in the room seem like a bit too much to me. The kitchen is emphasized twice, the video area has a different height... the TV also creates its own line...

I don’t want to emphasize it extra, I just want it to fit in the room and be low-maintenance.