When you’ve been in one job for almost ten years, especially if it was so formative to your career, you might want to take a clean break.
To move away from what you were known for, and try your hand at something else – build your skills, train some new muscles. In doing so, you might also decide to deliberately not return, even for a brief visit, for a long while.
Not because you don’t want to see the friends you made – you’ll keep in touch with them, regardless – but to make that clean break, clear and obvious. This is not all I can be, I can try something else and succeed.
Other times, a once in a generation pandemic hits, and you just don’t get a chance to have a proper farewell, and you have to wait until things calm down again, and circumstances allow a reunion.
You still miss the old lives, of course. And you lean on the experience of both to forge a new path. One where returns may be possible, one day, or not – but either way, you’ll be richer for it.