This is not something I have often struggled with, but when I have, I justified it this way. God describes Himself as being jealous, so there must be circumstances under which jealousy is appropriate. When I decided to write about this and began looking through the Bible, I believe I found evidence for that position, though I have not made a thorough study.
Sometimes we mix up the words jealousy and envy. Envy is not the same thing, and I do not thing we can find any justification for envy. For an eye-opening exploration of envy, I highly recommend Bob Sorge’s book on the subject. Envy is not something I thought I had a problem with until I read it. His book helped me to see it and deal with the flawed thinking that came from it. You can get the book in PDF form as well and screen readers will handle it just fine.
Jealousy arises when we feel that something that belongs to us is being given to someone else. We most often see it between lovers or spouses. God made provision for it in the law (Numbers 5.) He meant for romantic love to be share exclusively between two people. Most of us know this instinctively. We are hurt, threatened, and angered on a deep level when we begin to believe that someone or even something else is violating that relationship. I don’t see this portrayed as sinful in the scriptures. We get in trouble when we feel it unjustifiably or respond to the feeling inappropriately. One example of both occurs in Acts chapter 5. The Jewish leaders are jealous of the following that the apostles are drawing to Jesus. They respond by trying to destroy them. They were jealous for authority that did not belong to them in the first place. In romantic relationships we can ruin perfectly good ones when we see threats that are not there, responding in hurtful ways from our own insecurity.
It might be argued that the only one truly entitled to feel jealousy is God. He alone is truly worthy of our devotion. He alone can claim unqualified rights to all that we are and all that we have. If we have any right to jealousy, we usually do not handle it well. There is, however, at least one instance where jealousy is praised (Numbers 25:11.) I think that the only time we can be completely sure we are not acting in sin is when our jealousy is born of our love for God. When we are driven to defend that which belongs to Him in a manner consistent with His will and nature, we know that our jealousy is justified.