3. They become competitive.
According to psychologist Melanie Greenberg, people who are generally competitive are either insecure or arrogant and want to prove their superiority. If you catch an introvert who isn’t typically competitive, but start to notice that they want to compete with you, whether it’s for that job promotion, dream home, or even an ideal relationship, chances are, they are jealous of you. They see your life as something that they want for themselves, but instead of just mimicking it, they want to be better than you.
Sometimes, the competition may not always be so obvious, though. You might not even realize they are competing with you until you notice that everything you’ve worked hard for and gained in your life is suddenly being compared back to back with their own accomplishments. This may be casually slipped in dinner conversations at a social gathering or big events, and then you realize they were aiming for an upgrade in their image, rather than actually being your friend.