They did seem to drink an awful lot of tea in the castle. And it always seemed odd to me that Rumplestiltskin drank tea. He never struck me as a tea drinker. And it was odd that he served her tea when he threw her back in her “room” after they kissed. Maybe something in the tea protected them from the curse? Maybe Belle didn’t drink enough during her time at the castle to fully remember who she is but enough to have enough memories to be dangerous to Regina and to need to be locked away from the rest of Storybrook. Maybe what Rumple was drinking from his flask wasn’t alcohol but was his special tea.