Q: Does jealousy have a proper place in a relationship? A: Jealousy is a very widespread feeling, sometimes triggered by something totally imaginary, and sometimes based on something real. It's easy to say that a man should not be jealous of his partner's innocent friendship with another man, nor should a woman be jealous of her partner's admiring glances at a beautiful woman. So let's take an example in which there is some real ground for jealousy. Bob and Helen are in a serious longterm relationship. But Helen has to spend three months in Ecuador and Bob is unable to go with her. In Ecuador, Helen meets Juan, whose company she enjoys and who she finds attractive. Helen and Juan go to bed, using effective means of preventing pregnancy and STDs. Helen tells Bob about the affair, saying, truthfully, that it has made her less lonely, and has satisfied her sexual needs at a time when she couldn't be with Bob. She is in no doubt, however, that Bob is the one she loves. She and Juan both know that their affair is just something temporary that will finish when Helen leaves Ecuador. It's perfectly normal for Bob to be jealous. That's the way we humans are. There are relatively few mammalian species in which no one is bothered at all about who else their sexual partner or partners are having sex with. There are good evolutionary reasons why this should be so. The genes of males who spend time and energy rearing young that are not their own are likely to be eliminated from the gene pool. Females will be less likely to have surviving children if they allow males to have sex with them without first ensuring that the male is likely to stay with them during the period in which their child needs most help. Being jealous is a way of increasing your chances of having surviving offspring. So, unfortunately, is having a little bit on the side. That is why jealousy, and the behavior that gives rise to it, are likely to be always with us. Now that we have effective contraception, however, can't we put jealousy behind us? Can't Bob simply accept that Helen's affair made her time in Ecuador more enjoyable, but has nothing to do with her love for him? In an ideally rational world, that is what Bob would do. But because jealousy goes so deeply in our nature, it is unlikely that he will be able to completely avoid jealousy. And he may have some grounds to feel threatened. However, if Bob and Helen are secure enough in their love, and Helen can assure Bob that her relationship with Juan will end when she leaves Ecuador, Bob should do his best to avoid feeling jealous. But couples should know that feelings of jealousy are often more powerful, more difficult to eliminate, and more destructive of good relationships than we realize. That is why, in the real world, open relationships are not as easy as they would be if our emotions were under more rational control.