You pursue a dream, and it all appears to fit into place. You have what you want. You made a choice, and for you, it is the ideal opportunity at the moment.
You change or move only to have some elements altered. It may be people, circumstances, or situations. There are always many factors that play into your reality, and now it seems less than perfect.
In all likelihood, much of this new status centers on the old. Some factors may have altered, which may be significant, but much has likely stayed the same. Again, look at the people, place, situation, benefits, and circumstances, and many are likely to be entirely intact.
Just as you are aging and changing, so do circumstances. You would likely not want precisely the ideal as it was then. The model is what you have right now. What you do with it is your choice alone. While all else is changing, are you sufficiently too?