Jealousy.

Well well well, was chatting with Wyelin and suddenly she asked, “if you’re jealous, are you sinning.”
I told her, well, that’s a kinda’ difficult question, it can be a no and it can be a yes. But on top of that she highlighted why she asked this coz in Exo 20:5b “for I the Lord your God, am a jealous God” (this is talking about not worshipping any other God than Him)

Before that let me write a disclaimer: The following context are directed and may be accepted warmly mostly by Christians which is of the same faith as mine. If u happen to be of any other belief, it’s not necessary for you to accept the truth that I’ve written here. Nevertheless, I am not ashamed of the Gospel of Christ, so enjoy and God bless you. =P

Well, now lets take a look of WHY God will be jealous if you worship other gods. Because God is good, and He know the best for you. He wants you to only have Him as your God in your life because He knew that it is the best for you to be wholeheartedly obedient to your true creator!
He’s jealous because He wanted you to have the best (Him) but you choose the less.

Now, is it sin? No.
Why? Because the intention of the heart was for the good. It was out of His love for us.

Now, when a husband saw his wife blinking her eye to another guy and sipping from the same martini glass with him and getting drunk together and stuff, who on earth wouldn’t get jealous?! And who on earth wouldn’t get angry?!

Now, is it sin? I don’t think so. As long as the husband don’t have thoughts of killing the guy in the worse agonizing, tormenting death ever, he’s not sinning.
Why? Because his feeling of jealousy is out of love for his wife and not wanting to lose the woman he had made an oath to not leave each other no matter what until death sets them a part.

Now, lets say someone else of your age had a car and you don’t even have a bicycle. And you felt jealous and you planned a master plan to ruin your “friend’s” car. Poke the tire, spill paint on the window. Lol.

Is it sin? Oh yeah it is. (but remember where sin abounds, grace abounds even more, so if you happen to be someone I've described just now, repent and His grace is sufficient to forgive u... XD)
Coz you’ve entertained a negative thought of jealousy and put your thoughts into action.

The bottom line is actually the intent of the heart. Feelings comes and goes. We can’t like, be overly righteous and fasted three days three nights for “the redemption of our sins of jealousy” every time we feel jealous. But what we can do is to pray about it and give thanks to the Lord. Once we learn how to give thanks for the things we already have, we wont be jealous of material things or social status or anything. We’ll be happy of what and who we are.
God Bless. =)