Is jealousy a bad thing? Is it a good thing? Depends?
Some people say that a little bit of jealousy can be a good thing. Since it indicates that one cares emotionally for the other person. Jealousy is a normal trait in all of us humans, and it reveals itself on different occasions. You can be jealous in regards to your friend, or a romantic relationship. You could be jealous towards your parents, for example, you may think that your mother or father loves your brother or sister more than they love you. Again, some jealousy can be a good thing, just not to the point where it becomes destructive, this is when we become capable of doing just about anything to gain someone's attention.
Jealousy is a sign of doubt, or insecurity. Let me remind you that we all human beings have something interesting in us, just as we are all different. Next time you become jealous of someone else, just remember that you are just as interesting, or maybe more. If someone considers you a friend (or something else) is because they find something interesting in you, in general, they like to be around you. Do not try to impose yourself on that person. You have no right to decide who they should be friends with. In fact you are likely to chase them off if you act this way.
So a little jealousy is good, it can be cute but too much is a wreck. In a romantic relationship, it can feel good to know that your significant-other is a bit jealous. But when the jealousy is persistent, it can drive us nuts, and can even be enraging to some people. If they are with you is for a reason. Most humans are monogamous, and if they find someone that they like more, they are likely to dump their current relationship and pursue the other. When the jealousy is persistent, and has no basis, it can be reason for your significant other to want to end their relationship with you.
Go be a bit jealous, be cute about it, but trust others as well!