How about floor to ceiling drapes .... do you need what little light they admit into the room ? If so , maybe textured sheers ( not too sheer) to camouflage them. No short drapes. Or , if you could find one tall enough , a folding screen.

No don't need the light as it doesn't really let much in through there anyway. I just don't like how empty they look just like that. do you mean the drapes on either side or going all the way across so it would fall behind the bed too?

Yes, all the way, centered on wall to cover windows completely, they don't have to go all the way to the ceiling. Or I'd have them drywalled over I other window (s) are in room.

I would hang some art over it. Drapes would be dust collectors.

Yes-cover them with drapes, heavier in the outside, sheer ones closed over the windows.

I would probably remove them and replace with a stained or leaded glass piece.

I like the idea of maybe hanging some canvases but the window is not in the centre of the room as you can see so it would look like I've hung it crooked.

Anyone have any photos of the drapes idea? Just so I know I've got the same image as you both

Replacing them isn't an option as we're renting

Maybe a decorative grate that matches your style

You could put a stained glass panel in front of the windows.

How about framing them and adding plantation shutters?

Or adding colorful drapery panels with a collage of paintings, prints or photographs below.
Roman blinds.
Drapery panels with sheers in the middle.

Think grates and stained glass panels would not suit the decor as it's a very modern new build :(

I like the idea of hanging full curtains or sheers over windows and behind bed. Since the bed would then be placed off center of the curtain panels, add a substantial night stand on the side of the bed where the extra curtain shows. Then put a decent size lamp on the night stand. In other words, add to the space your bed takes up in the room by adding a good sized nightstand. That way your eye sees the bed and the nightstand together as one, taking up the space in front of the curtains.

For a renter, a simple fabric panel stretched over a wood frame would be easy, cheap, and removable.