Board Thread:General Discussion/@comment-25617908-20151208202256/@comment-8345449-20151209052404

The heart sharing thingy would only work if the two people sharing were in love, such as in Charming and Snow's case. Emma cares about Graham and Neal but her true love is Hook now (at least that is what the show has been indicating). So it would only work with Hook.

Also, I think Emma only meant to be metaphorical about sharing a heart. I think what she means is that she will split half her life-span or lifeforce with Hook. Sort of like what the Hero does with either Erana or Katrina in QoG5.