Some people seem to have no jealousy; it's as if they didn't get
     that piece installed at the factory.  Others, including some
     long-term polyamorists, feel jealousy, which they regard as a
     signal that something needs investigation and care, much as they
     would regard depression or pain.  Jealousy is neither a proof of
     love (and this is where polyamory differs from possessive or
     insecure monogamy) nor a moral failing (and this is where
     polyamory differs from emotionally manipulating one's partner(s)
     into relationships for which they are not ready).