Well, it would make room for Emma to be Henry's only mommy. And with the Wicked Witch on her way perhaps there's only room for one beautiful, dark power. But what would Once Upon a Time be without Lana Parrilla's Evil Queen?
Maybe you should take a piece of advice from a man who has pushed away every chance of happiness because it was never enough. If it's within your grasp, if you know where it is and who it's with, then you should run to it, grasp it and never let it go.