Board Thread:General Discussion/@comment-26184894-20150813005948/@comment-34662427-20180211145615

in the the first episode rumple told regina that in order to cast the curse she had to kill the one thing she cares about in the world, which was her father

i think rumple wasn't able to cast the curse because he didn't have anyone who he cared or loved, his son was lost which was the one person he truly loved and he was the one he was looking for.And as for Belle, when he met her, he cared only about power and a to create the curse, and he didn't want to fall in love with her, and when he did after he sent her away, Belle was believed to be dead (even though she was locked by regina) thus he didn't have someone to sacrifice. And he couldn;t use Zelena because she was full of hate and envy and she didn't love anyone also.