I think Morgan cursed it so she would fall into the lake or use it as an excuse to get close and push her in and drag her down with magic BloodCoveredAngel
Same I am pretty sure the next chapters are going to be how Morgan keep on pushing the princess and Arthur together and Arthur and Lin apart I think that she's trying to make Lin look bad so much that her title will be removed and that she might get vanished or something
They're just going to forget about her necklace!?