Paint or paper this wall - which one is it?

[Stillwaitingforsummer]

We're wallpapering the cream wall on the photo. Just one wall. The part to the right that had been painted grey though, is it part of that back wall so paper it, or part of the painted wall which has a door next to it?

I would paint it

I wouldn't wallpaper the grey part

Paper the side at right angles to the cream wall and leave the other side.

Thanks. I was expecting people to say it needed papering.