I've found it helpful to utilize evolutionary concepts when considering human behaviors, as everything we feel is the result of hundreds of thousands of years of selection pressures. Nothing inside us has emerged by magic: just as our bodies have been shaped by evolution, so have our brains.

When we realize that from an evolutionary perspective we are the means of DNA passing itself into the future, it becomes evident that behaviors which on average result in this happening will spread throughout the species and become normative whereas behaviors that on average do not achieve this outcome must pass from the gene pool and thus not be in our repertoire.

With this basic concept in mind, we can look at jealousy.

Everything indicates we humans are a semi-monogamous species: the relative sizes of males versus females, the size of male testes, and our mate-guarding behaviors. Males must attempt to ensure their sperm is successful (deny other males access to one's mate) while females must attempt to ensure they get both the best-available sperm and the best-available commitment to the relationship in order to maximize the chances of their offspring's survival. It is evident therefore that each will pursue very different strategies (males seeking to copulate with as many females as possible while females attempting to mate with desirable males while hiding this from the male who is providing resources). Both, in order to support these strategies, will experience jealousy that will impel them to perform the gender-specific behaviors that on average promote their unconscious goals.

What we believe about ourselves, and what is actually observable behavior, are usually two completely different things. We would be wise to bear this in mind when discussion emotions and strategies for dealing with them in a world that in no way resembles the environment in which we evolved and for which we remain hardwired.