Christians are not allowed to be jealous of what others have, whether it be material things, situation in life, bodily health, or a successful life. This kind of jealously ultimately arises out of discontent for one’s own material things, situation in life, etc. The ninth and tenth commandments forbid covetous desires of any kind and instead require us baptized children urge others to be content with their own situation as well.
God alone reserves the right to be called “Jealous”. “I the Lord your God am a jealous God.” In His relationship to His people, He is husband and they are bride. He is Father and they are son. God’s “jealousy” does not arise out of a sinful discontent of the heart (obviously) but has to do with His intense love for His bride. For the Church to turn to other gods is tantamount to spiritual adultery, and makes God jealous, because as His bride the Church is to be devoted to Him alone.
I would submit though that in so far as the relationship of husband and wife reflects that between Christ and His Church, there is a sort of righteous jealousy that husband or wife experience when one or the other is unfaithful. If a wife turns from her husband and jumps into bed with another, does not the heart of a husband rightfully burn with jealousy for his wife’s love and devotion? This kind of jealousy is born out of the intense love that is experienced between husband and wife. Likewise, does not the heart of a woman rightfully burn with jealousy when the eyes of her husband are directed toward another?
This jealousy that a man or a woman may experience when his or her spouse is unfaithful is like unto the jealousy that God has for His people when the attention of their hearts is diverted away from Him to others. I would say that not only is such jealousy completely natural, it is not sinful. There may be other sinful emotions that accompany this kind of breach in fidelity. But I am inclined to think that it is not wrong for a wife or a husband to be jealous for the other’s love.