Why does Emma regretted about her wedding? Have you ever regretted of anything you have done?

Emma regretted 'cause she was in two minds about her step, she didn't know whether she acted in a right way, may be she was in a hurry and could find a better man. She was afraid of being unhappy in the marriage, not share love with her husband. She might have frightened that her life wasn't so interesting, full of freedom. It's difficult to judge her action.
Pshychologyst are saying unanimously one thing: "Never regret about what you've done" . I'm a kind of person who plans his actions and sees the result of them. But,anyway, sometimes I regret that this or that thing I could do in a right way... That is our life, it consists of trials and mistakes.