A return ticket is a promise made to a version of the journey that has not happened yet.

Buying the return is a commitment made on behalf of a person who has not yet had the experience. You decide now when the future you will want to come home, though that version will have been changed by everything in between and may want something different. Planning always binds a self who could not be consulted.

So make your commitments with a little slack where you can, and treat the plan as a good guess rather than an obligation. When you find yourself resenting a decision you made months ago, remember that you were doing your best with what you knew, and that changing it is sometimes the honest response rather than a failure of discipline.