She knew the curse would require his sacrificing the heart of the person he loves most. At that point in time, that wasn’t actually possible for him–he had just lost the only person he loved.
Part of me wonders if that’s part of why he sent Belle away–fear that if he actually did give in and let himself love her completely, he’d destroy her.
Or maybe BF knew he couldn’t do that to someone he really loved (cuz, seriously, the worst thing he was ever able to do to Belle was send her away and shake her a bit, and the worst thing he ever did to Bae was let go of him–big things but not intentional harm, just fear taking over–while Regina was actually capable of taking her father’s heart and killing him while loving him). Of course there’s the complication of what he ultimately did to Cora, but love can turn to hate pretty quickly under some circumstances. (And it wasn’t true love, even if neither was playing the other.)
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