What of jealousy? It seems to be one of the bug-bears of relationships.
Jealousy is an expression of immaturity, but not many of us are without it in some form or another and so we must come to terms with this emotion. It can become an all-destroying monster, capable of ruining the best of relationships, but it should be recognized more as a challenge to help us grow in maturity and personal knowledge. It cannot diminish until we finally accept that we cannot possess another human being. We have to learn that loving others is to want them to be themselves, however painful this may be to us. Love must be set free and only when it returns in absolute freedom can we know we have the real thing.