jealousy.

1. feeling resentment against someone because of that person's rivalry, success, or advantages.
2. feeling resentment because of another's success, advantage, etc.
3. inclined to or troubled by suspicions or fears of rivalry, unfaithfulness, etc.
*source: dictionary.com

Jealousy is one of the seven deadly sins.
really? i don't know but i've heard of it

and the word Envy is the synonym of Jealousy.

*incomplete*

everyone will get jealous somehow,
if you're denying it, pls feel free to tell me why. =)