Let me tell it the way I see it...
As a child, Zelda is incredibly frightened. She has prophetic dreams and senses evil in a man that is trusted by her father. When she tries to warn the adults around her, they don't believe her. When she meets Link, she recognizes him as the heroic figure from her dreams which gives her hope. So much hope that she can barely contain how excited she is, and goes all out with their "secret plan" to get to the Sacred Realm and obtain the Triforce. What she doesn't realize is that's exactly what Ganondorf wants them to do: in fact, he's already caused problems for the owners of the Spiritual Stones specifically so that Link will solve them and get the Stones. Link and Zelda were naive children and Ganondorf took advantage of that to trick them into opening the seal to the Sacred Realm.
After that happens, Zelda realizes the enormous mistake they made, and does everything in her power to set things right. She trains in the art of the Shiekah and disguises herself as a man to avoid being found by Ganondorf. I think it's implied that along with Impa she has been helping a lot of people and protecting the fugitives from Ganondorf's reign, and that her helping the resistance is a big part of the reason why Ganondorf hasn't taken complete control of Hyrule yet even after 7 years. Then she assists Link in awakening the Sages by providing him with wisdom (appropriately)
After Ganondorf is defeated is when Zelda reveals her regrets to Link. We can see her mixed feelings in the scene: She is relieved that Ganondorf's reign is finally over and that Hyrule will be at peace once again. But she can hardly feel victorious, because she feels incredibly sorry for being partly responsible in the first place, and for robbing Link of his childhood. So she sends him back in time, along with instructing him to seal the path between times, shutting her timeline off from his. It's hard for her to do because she has developed a strong bond with him and she will never see him again. We can assume that she continues mourning her regrets after Link is sent back because she is nowhere to be seen with the citizens of Hyrule nor the Sages as they celebrate Ganondorf's defeat.
So, to run through the major emotions we see Zelda express over the course of the game:
Fear: Caused by the prophetic dreams, Ganondorf's presence in the castle, and nobody believing her.
Naive hope: at Link's arrival and with her plan to obtain the Triforce to defeat Ganondorf
Bravery, Persistence, and Ambition: as Shiek (probably partially fueled by a hidden regrets and guilt)
Seclusion, antisocialness: to avoid detection by Ganondorf
Cautious partial relief: at Ganondorf's defeat
Deep regret and sorrow: because she feels responsible for her mistakes, she feels that she robbed Link of his childhood, and she realizes that she will never see Link again
Repentance: by sending Link back and having him close off their timelines in order to prevent her mistakes from happening in the child timeline as well as to let Link live his childhood