Honestly? Now that I've laid down enough foundation to reliably feel that I can and will be fully happy and fulfilled even if don't have this or that person in my life, I'm starting to come around to jealousy -- and anger from jealousy -- as wonderful and healthy emotional tools for checking and resetting out-of-balance priorities.
To be clear, most typical behaviors from jealousy are still bad. Valid options are
honestly, non-manipulatively, and non-coercively communicating; and
setting ethically sound boundaries.
But if you can keep your use of those emotions healthy, it turns out they are beautiful, clear signals of over-extension. They're telling you that you're investing at a level that you'd only be happy with if you got more.
And from that lens, it suddenly makes sense why so many people react to jealousy and its anger with accommodation rather than disgusted rejection. Because before words even existed, evolution was using jealousy as a direct chimp-level signal that the other party is willing to walk away if not accommodated.