I was thinking about this today. I thought about what Mr. Gold said to Emma, explaining why she was the savior in the finale. It’s because Emma is the product of True Love and I wondered, okay, if everyone in fairytale land has true love, wouldn’t that also mean that Cora and Henry once had True Love for each other but TL went south really quick since they were poor? And if they did have True Love once, then Regina would also be a product of True Love as well.
I’m also willing to bet the reason Cora didn’t want Regina marrying Daniel was to keep history from repeating itself.