I'm lost now...So can someone help me with the story here?
So the portrait is the host of a powerful entity, possibly a demon. Those who looks at the portrait will seem the image of their lust/whatever they consider attractive. Yet the entity in the mirror transforms their owner into a different person that wasn't in mind. They will shift their gender over?
Then why use the lustful eyes curse ? Did I misread something here?
@Wubstep It's possible the painting only changed itself to affect the wife so that she'd allow him to put the painting in their bedroom. The two ladies at the fleamarket both comment on how embarrassing the painting is.
The painting is trying to get him to free it from the "Aether" and when he refused it started fucking with him. I wouldn't be surprised to find that he's still in the Aether and not actually back home at all.