Jealousy. I've wondered about this, wondered where it came from. I've had girlfriends who'd been jealous, some more than others. And I'd been jealous myself. And of what value was it?
And I had an Epiphany.
Jealousy is the imagining of what we would do were we in our partners position.
It's the projection of our worst selves upon others. And, if we've made a bad match, maybe we're right.
And then there is lack of jealousy. In which we project our best selves upon others, imagine that they would do what we would in similar circumstance, by "we" I mean the best of "we", the "we" possessed of those noblest of qualities: love, loyalty, fidelity and honor.
And if we've again made a bad match, maybe we're wrong.
But I understand it now.
To boil it down, make it quotable, try this: "jealousy is the presumption that others are doing as we would do in their position."