Likewise the restless the unicorn it is said can only be brought to bay by innocents (generally-speaking virgins, quite often female). Like a unicorn Regina has a restless nature that only Henry has been able to calm. While attempts made by anyone else have all ended with them getting burned. Henry’s childhood innocence has calmed Regina’s spirit and his believing heart give her hope. Woe betide the rest of the family if that changes.
They seem to be dropping hints that that is indeed going to change. When Pan said to Emma, “You haven’t forgiven your parents and Henry hasn’t forgiven you” it sounded like he is going to try to sew discord between Emma and Henry. If so, it stands to reason he would also want to isolate Henry from Regina. It seems likely that will tie in with manipulating Henry to become the “savior of magic” (which will no doubt turn out to be something much darker) but I haven’t been able to devise any more specific speculations.