Wdym twin ?
But Why did she say “see you tomorrow” when the curse finally broke and she killed herself? There will be no more tomorrow if the curse have been broken
remember the meaning of Wolfsbane? That meant, "Never again I'm letting the one I love, come back to me." and I'm assuming she either meant that he won't see her again or he would follow her to death.
1) She died of snake bite in the forest Orpheus suggested
2) he rescues her from the underworld, but didn't follow directions and looked back. Cursing them.
Her living and dying was something FL didn't choose, ML made her go through that (even if he didn't know she remembers her deaths) and at some point he just thought about protecting her as a duty, not as a love. Their love died and they didn't know, they just force themselves because of his ego of not letting her go.