Jealous

Jealousy is an emotion, and the word typically refers to the thoughts and feelings of insecurity, fear, concern, and anxiety over an anticipated loss of status or something of great personal value, particularly in reference to a human connection. Jealousy often consists of a combination of emotions such as anger, resentment, inadequacy, helplessness and disgust. In its original meaning, jealousy is distinct from envy, though the two terms have popularly become synonymous in the English language, with jealousy now also taking on the definition originally used for envy alone. Jealousy is a typical experience in human relationships. It has been observed in infants five months and older. Some claim that jealousy is seen in every culture; however, others claim jealousy is a culture-specific phenomenon.

Jealousy can either be suspicious or reactive.

Jealousy is often reinforced as a series of particularly strong emotions and constructed as a universal human experience; it has been a theme of many artistic works. Psychologists have proposed several models of the processes underlying jealousy and have identified factors that result in jealousy. Sociologists have demonstrated that cultural beliefs and values play an important role in determining what triggers jealousy and what constitutes socially acceptable expressions of jealousy. Biologists have identified factors that may unconsciously influence the expression of jealousy. Artists have explored the theme of jealousy in photographs, paintings, films, songs, plays, poems, and books. Theologians have offered religious views of jealousy based on the scriptures of their respective faiths.

Sexual jealousy may be triggered when a person's significant other displays sexual interest in another person. The feeling of jealousy may be just as powerful if one partner suspects the other is guilty of infidelity. Fearing that their partner will experience sexual jealousy the person who has been unfaithful may lie about their actions in order to protect their partner. Experts often believe that sexual jealousy is in fact a biological imperative. It may be part of a mechanism by which humans and other animals ensure access to the best reproductive partners.

It seems that male jealousy in heterosexual relationships may be influenced by their female partner's phase in her menstrual cycle. In the period around and shortly before ovulation, males are found to display more mate-retention tactics, which are linked to jealousy (Burriss & Little, 2006). Furthermore, a male is more likely to employ mate-retention tactics if their partner shows more interest in other males, which is more likely to occur in the pre-ovulation phase (Gangestad, Thornhill & Garver, 2002.)

...
Wikipedia