The very fact that Daniel suggested to Regina that she “love again” makes me believe that ultimately it IS possible, even in this universe, for someone to have more than one true love. And it’s clearly possible for love to go one way (I think it was that way for Rumple with Milah, definitely for Sidney with Regina). Then there’s the question of whether Graham + Emma was true love or not–kissing her brought his memories back, but was that because she was the savior or because they were falling in love, or both?
Also, TLK seems to have quite a few caveats–both hearts seem to need to be entirely open to one another for it to work, and it can’t cure death/deadly wounds/poison the way it does curses.
Keeper of Belle's Gold magic, sand dollar, cloaks, purple FTL outfit, spell scroll, library key, copy of Romeo and Juliet, and cry-muffling pillow, Rumple's doll, overcoat, and strength, and The Timeline. My spreadsheet: https://drive.google.com/file/d/0B6r8CySCCWd9R0RUNm4xR3RhMEU/view?usp=sharing