Fact: Ymir stayed in the path for 2000years but that's only for human world, there is no time concept in path, so she technically was in there for infinity.
For 2000 years alone in a place like this!! Not just that, those 2000 years were only according to human world. In paths, the time is slower, so that means she was there for billions, trillion years, or even more!!!! Surely she must have gone insane in all those years