Another response for the Ask Box Ficathon over Tumblr, enjoy!
Disclaimer: I owe nothing. Not even the plot, I just fulfilled it, please don't sue me. ;)
To destroy a curse
If this really was a fairly tale curse, then it took Emma long enough to realize how to break it. Henry believed she somehow had to destroy the Evil Queen, or something along this thought, but violence, no matter what kind of it, was never the way Emma used to solve her problems. So she took some time to think about what to do about this alleged curse and the best way to finally make Henry see that his mother wasn't a bad person, even less the Evil Queen.
So she did what she did best, observed Regina. Even with all the duties of the Sherriff, Emma took her time to actually observe and try to understand Regina Mills.
She was a lonely woman, desperately trying to get some love from her son because if she couldn't have anyone else to love her, at least her son should freely love her.
Emma also realized Regina was a beautiful woman. All the animosity aside, Regina had a nice body, nicely shaped legs and a voice that gave Emma chills the first time she heard it.
All the observing made Emma draw one conclusion: Regina Mills needed to be loved. She needed to feel it, be able to see it and believe on the love, after all, it was a freaking fairy tale and all fairy tales ended with love.
It had taken her a while. First to convince the woman that she didn't want just to fuck her. It took her even more time to convince Regina that she wasn't going to leave town and accept that she was there for her. But ultimately, she still didn't know if Regina actually believed her when after a special lovely love-making session, Emma whispered the "I love you" on her ear.
It was a fairy tale, if love was the only way to save the good guys, then probably love would save a desperate soul begging to be loved.
To destroy a curse, love might be the way to break the curser and give her the happily ever after she deserved too.