What is Jealousy?
Jealousy is like a hot pepper. Use it mildly, and you add spice to the relationship. Use too much of it and it can burn.
Ayala Malakh-Pines
Jealousy is a negative feeling in interpersonal relationships which appears when there is a lack of love, attention, respect or sympathy from beloved, while another person allegedly or really receives them from him/her.
Jealousy is an ambivalent emotion, it has two poles: love and hatred.
Some jealousy is needed in working and healthy relationships. It shows that the partners love and don't want to loose each other. But the absence is not a good sign. It means that partners don't care about each other enough and that they have some problems in their love relationship.