Is jealousy natural?

Jealousy is an emotional response that arises when a person perceives a threat to something he/she considers him/herself. 

This time I will talk about jealousy in couples. Jealousy that arise between couples, usually produced when you do not have much confidence in the relationship or one partner is believed inferior to the other. When a couple does not have much confidence often think the worst on both sides, because not knowing everything that happens to him or her, or what can get to think he or she, this may influence when they communicate with other people. 

If a partner feels inferior to his partner, always thought he or she wants not enough and that he or she could be with someone better than him or her. I think it's one of the worst feelings you can have in a couple, since many times because of jealousy, many couples are torn apart or many people come to hurt their partners for this. 

I think jealousy are both boys and girls alike, is also always say that girls are more jealous than boys, but this is an urban legend. Many men come to attack their partners for them.