Board Thread:Questions and Answers/@comment-25322628-20170113025521/@comment-31951459-20170517091236

Arshpar wrote: she was an idiot to go with Bert and Reiner thoough

I came across the chapter again where she left with them, and the narrator says "At that time, we didn't understand Ymir's actions." This implies that her exact reason for leaving with them will be made clear in the future. I'm still feeling her death but I have hope that we will be given proper closure.