It all depends on what form the jealousy is being displayed.
On one hand it's a sure sign that the other party cares so much about you, and yes somehow that drives them to want to be the best they possibly can so as to keep your interest focused on them.
While on the other hand, it needs to be carefully watched. Because some toxic people use it as a way to be domineering in relationships. They use it as a tool to monitor your every move and lifestyle, and that's really creepy. Trust me I speak from experience,..
In relationships the margin between jealousy and trust is very slim, and needs to be watched closely.