Maybe if you run it along the seam between the ceiling and the wall it wont stick out as much?
Another option would be to just embrace it and make a coool pattern with it or something.
Ethernet is so much better than trying to use wifi, I hope your partner understands.
Other options include drilling thru the walls and patching up the holes before you move out, or finding someone else who understands your desire for reliable low latency connections, who loves you more than they love wall aesthetics