Board Thread:Spoilers!/@comment-24674051-20150720164321/@comment-5679696-20151001204022

Uhm... No, any true love kiss would not break the Dark Curse, or at least not the first one. That was because Rumple designed it for Emma, and only Emma, to be the Saviour. Her true love would be the only one that could break the curse.

Now, for the second curse, Regina broke it because either:
 * 1) No saviour was specified, therefore any kiss could break it. This is almost impossible, as it would rule out Mary Margaret and David (and every other true love couple in Storybrooke) kissing during that time span, which would be absolutely stupid.
 * 2) Regina was the saviour because of something we don't know about the second curse.
 * 3) Maybe Regina had something to do with it, and we never learnt. She was there when it was cast after all.
 * 4) Or perhaps Zelena used that drop of blood she had a monkey steal and dropped it together with the memory potion, to make her sister the saviour. This wouldn't be too far fetched, since we didn't really see Zelena do anything else with the blood (writers implied she needed it to confirm their sisterly bond, but who knows?), and it would be totally like Zelena to have Regina break the curse only to then take everything away from her.
 * 5) (my personal favorite one) True Love Kiss is a two way thing. What if it was Henry's side of the kiss that broke the Curse? He's the Saviour's son, so he is at least 1/2 product of Snow and Charming's true love, and therefore, have Saviour blood running through his veins. So his true love for his mother broke the curse when she kissed him.