Liberation from life
Sun looked at the raft that was sailing away. She thought of her life, how Jin had treated her all those years. Still she couldn't run away from him weeks ago at the airport. However, now she was left alone anyway. She was free to do what she wanted, where she wanted to go and with whom she wanted to talk. This was actually a freedom from her life, which she had always lived so unhappily.
This gave her a happy feeling, but still she was scared to do it. He could find out about all the things she'd do, then he would never come back to her. Nevertheless, he could also not know about it forever, but then she was lying, lying to the man she had always loved so dearly.
This liberation from her life was actually quite complex and didn't feel good. She could be free, but once Jin would come back again, and once more she would have to obey his rules. Therefore, it would probably be better if she just carried on now as she was supposed to. She had the freedom, but used it wisely and freed herself from her old one, and started with a new one in which she would do whatever her husband wanted. For once, she would make him happier then he made her years ago with just a flower. This would be the liberation of her old, discontented life.