Just had a thought. We all know the Blue Fairy likes to interfere in business that doesn’t concern her (Dreamy/Nova and Rumple/Bae), What if Blue Fairy tells Rumple that Belle is better off not knowing him?
Blue’s interference has already screwed up Rumple’s relationship with Bae, there’s no way that he’d let her screw up his relationship with Belle.
Killing the Blue Fairy, perhaps in order for Belle to regain her memories, will not only put a divide between Rumple and Bae but could also create friction between Rumple and Belle.