Jealousy allows for no rivals in intimate relationships. This is why God is jealous when His people embrace idolatry.

"…You shall not worship any other god, for the LORD, whose name is Jealous, is a jealous God…" Exodus 34:14

Covetousness and envy are wrong, but appropriate jealousy is a dimension of passionate love. To be jealous of a business rival or of someone considered more attractive is actually to covet, and therefore a violation of God’s commandment. But if a third party intervenes in a marriage, the offended individual will be jealous, if love is present. Jealousy allows for no rivals in intimate relationships. This is why God is jealous when His people embrace idolatry. Be grateful He is jealous for you because it’s a sign of the intensity of His love for you.