I said that not all jealousy is driven by low self-esteem; and that's right. People with quite high self-esteem can experience intense jealousy if they tend to feel they themselves must always be the center of things. People like this tend to look at other people as material property. And maybe they just don't want to share that 'property', even as far as letting their partner innocently smile or socialize with another person. Perhaps as a kid they were a little spoilt.
But people are not objects or toys to be constantly guarded. To love someone properly, we need to be prepared to lose them. What? Am I mad? Sounds like it, you might think (and I do have my moments), but hear me out.
Anger, fear, and jealousy drive out love; and love needs a strong dash of fearlessness to flourish. Okay, so you fear losing your loved one to someone else (and possibly fear how this will make you feel about yourself). If you must keep using your imagination, use it to imagine the 'worst' happening and you still being okay; not just surviving, but thriving in this imagined scenario.
It might sound strange to say that jealousy is more about self-love than real love for another person, but jealousy does make us focus more on our own feelings than the feelings of the other person. Overcoming jealousy isn't about making your partner face the wall in restaurants or trying to prevent them ever looking at anyone else; it has to be about you managing your own emotions.