How do guys get jealous?

First of all, guys and girls get jeolous(yes i am a guy). Well this is why people get jelous.

Most people are insecure atleast to a point, so if they get the idea that their girl/boy friend is cheating on them they get jelous. It also gives them the idea that they arn't good enough for you.

But sometimes its a sign of an abusive partner. If this person must always know where you are and what your doing and who your with, you should get help to leave the relationship.