Im not 100% sure.Hmm, what if this is the ultimate form of psychological manipulation. She knows he'll kill himself to get her back cause he needs her power and next time let her have her way. After all, i doubt she'd just "kill" herself after waiting centuries to be free.
Look her view point. She trapped soo long yet she cant even kill herself.
The only hope is a prince. And she devoted 100% for him. The hard rejection for her just mean there is no reason to live. She finaly can die and there is no reason to go forward. (For that long time there probably nobody alive who she know )
Im certainly she simply unhinged about death. If our hero just leave and create a save point its fine too for her. But lets face it he will reset to save her.