Questions to consider about our path and the paths of others with which it crosses...
Do things run their course, or is their course never run?
Does this only happen within a pocket of time, a phase or stage of life, or is everything one unit?
Do people really change, or do they become more true versions of who they were always going to be?
It feels right that things run their course within a phase of life. This goes back to what I've always believed about looking back and understanding how small you were compared to what you are now. I'm not sure I believe people change, although I do think I believe people grow. There are a lot of things I've experienced in my life, a lot of phases/stages, that I've come out the other side of having been a better person who has grown a lot as a result. There's almost always some collateral damage, but that might be what's required of us to grow (this is a good example of something being necessary vs. sufficient - collateral damage is necessary for growth (although I've never truly mastered this idea of necessary vs. sufficient, so who's to say)).
In the universal scheme of life, we've never truly run our full course with ideas or people. We're always evolving, always understanding more, and it's simply in smaller phases/stages of life that mini-courses are run. Checkpoints, if you will. You experience something with someone, that mini-course is run, and you come out the other side having grown as a person, with a little baggage. But our full, universal courses are never run.
