For the first time in her life, Emma Swan finds herself in love with her now confirmed True Love. They have a house to themselves and they can finally start thinking about their future together.
For the first time in her life, Emma Swan feels loved - by her boyfriend, by her parents (the ones she’s been searching for her whole life), by her son and by her friends. All the holes and voids in her heart are slowly starting to be filled - and then she learns that regardless of what she does, she’s going to die. Soon. There’s no escaping it. And suddenly her entire world, the one she always dreamed of having, just collapses.
So what does she do? She tries to preserve it the most she can, she desperately tries to keep everything as it is. That way she can enjoy the genuine and natural current “ideal” status of her relationships with the ones she loves. Why? Because she knows that the minute she tells them about her doomed fate, the relationships she has always wanted to have will change : everyone will be heartbroken, they will treat her differently and possibly put themselves at risk to save her from her fate. And Emma just won’t have that. So she’ll do whatever it takes to keep things as they are, even if that means keeping everything for herself and lying to them. Anything but causing them any more pain and destroying the near bliss she’s always dreamed of having.
Even though she’s completely wrong by lying to Killian about it, it is human and it makes sense.