Is it okay to be jealous? The 10th commandment says you shall not covet your neighbor's house, wife, servant, etc. (Ex 20:17), so we shouldn't desire what others have, right? Would it surprise you to learn that in that same chapter, in the same set of commandments, God describes himself as being a "jealous God" (Ex 20:5)?
In English, the meaning and usage of words changes over time. Only a few decades ago, the words gay and queer we very common words to describe being "happy" and "strange" (respectively) and had nothing to do with somebody's sexuality. In the 1800, for someone to condescend to someone else's level was considered an honor, because it meant that they were including you in something even though they belonged to a higher social order.
When God describes himself as being a jealous God, he means that he desires him people only for himself and doesn't want to "share them" with other gods or idols. Is this a bad attitude to have? Absolutely not! After all, he is our God, and he created us to serve and worship him.
I am jealous of my wife. She is my wife, and I don't want anybody else to have her. That doesn't mean that I secretly dig through her emails or keep tabs on her because I suspect her of anything, it just means that I rightly desire all of her affection for myself, and in turn give her all of mine.
I am jealous of my kids. They are my kids, and I don't want anybody else trying to be their parents. I still trust other parents to keep an eye on them and teach them things at school and church, but I do not expect or want other parents to love my children as their own.
So there are times when jealousy is not only okay, but good. The problem is that in modern usage, we have come to equate jealousy and covetousness. Jealousy is NOT good when you desire something that doesn't belong to you, or when it causes you to be mistrustful or mean. Biblical jealousy is merely desiring what is rightfully yours.