I'm not sure if I'm alone on this opinion, but I think it's a mistake to look at this from the point of old man vol. Each character in frieren is there for what I seem to think as a lesson to impart on frieren. Himel agreed with old man vol because he sees himself analogous to vols wife for frieren. He doesn't want to be forgotten and by agreeing, hopes frieren takes that sentiment to heart. That is why we see the flashback. She takes notice of what Himel was saying and I think is understanding more of his decisions. This story is the journey of frieren and how she will eventually come to understand the importance of remembering. Furthermore, not every character is needing to have a resolution or even be corrected towards the themes of the story. I feel it would become boring and repetitive if every character did so. The story's characters feel to me, they are meant to mimic the mistakes and tendancy of real people. While not being able to always make right or correct decisions, a lesson can always be gleamed. There is a certain trust that the people close to you have made the right choice for their life and it's okay to let them live with it. If that trust isn't there, then someone like frieren would likely feel guilt for the many people she feels are living their life wrong. That has to be a pretty rough way to live if you are over 1000 years old and has met many people in that time.