Jealousy is broadly defined as the response to a real or imagined threat to a relationship. Some would say that jealousy exists because it is a good mate retention strategy. It helps us keep our partners because we become more attuned to potential threats to our relationship.
A partner's jealousy can be seen as a sign of love or affirmation of commitment. About 75% of people said they tried to make their partner jealous at one time or another.
Although a little jealousy might remind our partner that they don't want to lose us, but in general jealousy seems to be bad for relationships. Jealousy is more often associated with arguments, breakups, and aggressive behavior and when we feel jealous we may question the level of commitment in our relationship.
One of the most important factors in determining whether jealous feelings are good or bad for your relationship is how you (and your partner) express or respond to jealousy. Partners who communicate about their feelings of jealousy are typically more satisfied in their relationships than those who act distant or avoidant. If feelings of jealousy make you pay more attention to or show more affection for your partner (in a caring and not possessive way, of course) this is more positive for your relationship than if you start a fight with your partner or accuse him or her of betrayal.
So it turns out in my opinion, a little jealousy can remind us that our partner is important to us and that we value our relationship with them. But, more often, jealousy seems to be associated with relationship dissatisfaction, feelings of insecurity and conflict. Most important, it seems that the degree of impact that jealousy has on our relationships is strongly influenced by how we respond to feelings of jealousy.