I have a color like this on the walls of my game room, with espresso colored leather sofa and chair, and blue/teal/lime accents. I used sheers the same color as the background color on your sofa, and the room looks great. However, you could go with black, too, depending on the carpet or flooring.

nice, light coloured tiles

But if you simply cannot remove the washbasin, replace this configuration with a decorative countertop version - a nice stone counter and earthenware basin as shown in the pictures. A more econimical, but not so pretty option is to leave everything as it is and add a low partition about 3'6" high on the left that shields the washbasin from view. You can continue the tiling (ideally a faux brick or slate- NOT white) across the niche on all three walls. Paint the door in a dark shade too -like charcoal grey so that it does not look bathroom-y. Add a wooden moulding around the door frame and paint

where we use artificial grass, laminate flooring, marble countertop & mood lights