So I’m going to sound very rude, but I don’t think any of this is your doing.
It just looks so depressing. Fourth bedroom looks tiny and I was one of many people who didn’t spot it at first. What would be the consequences of calling it a three-bedroom and pleasantly surprising people with how spacious it is?
No curb appeal, but that’s partly down to taking the pictures on a dull day.
The room with the twin beds in it looks terrible. If possible I’d take one bed out and make up the other.
All photographs should be taken from sitting down height. At the moment you end up focusing on the ceiling and the ceiling light, which is on but the room still looks dark. Taking photos from high up also stuffs up the perspective, so the corner loo in one of the bathrooms looks tiny.
Is there a circular patio in the garden? Because it’s been overtaken by weeds. Garden also should be photographed as if sitting in it, especially if the view really is nice (difficult to tell from current angle).
The odd table lamp and indoor plant/flowers would make the whole house look cosier and more lived, though I understand why it doesn’t. If your ex wants to achieve the price he wants, though, he’s got to work for it.