In The Long Night, at the end, we see Melisandre
walk out of Winterfell into the snow-covered landscape and commit suicide. She removes the collar imbued with the magic of the Lord of Light that kept her young, thus the years catch up to her and she quickly falls down on the snow, reduced to an incomplete skeleton it would seem.
It makes little sense to me that she would do that after managing to survive through the whole battle. She did told Seaworth that she was going to die, when she arrived at Winterfell, did she mean it that way? Was this planned all along despite their low probability of survival?