It's a terrible behaviour that will undermine your confidence and is meant to assert their dominance. That's not something that should ever exist in a safe, loving relationship.
Flirting with others is a big red flag, especially if they're doing it in your presence. It's not only disrespectful, but it's also an attempt to bring out jealousy and insecurity in you.
Telling you that you're overreacting or dismissing your feelings, especially when it comes to social situations, is a serious form of emotional invalidiation.
Irrational jealousy and possessiveness is a dangerous trait. If they start accusing you of flirting or being too friendly with others, take it as a major red flag.
Your ambitions and accomplishments matter - and they should be celebrated by your partner! If you find your partner doesn't care about your achievements
If your partner repeatedly interrupts you while you're speaking or doesn't allow you to finish, it's similar to talking over you - it shows they have a lack of respect for your thoughts and voice.
Consistently ignoring your needs, whether emotional, physical, or otherwise, especially in public, indicates a self-centered attitude.
Showing a blatant disinterest or mocking your hobbies and interests, especially in social settings, signifies a lack of support and understanding.