Parents and kids usually have difficulty during the teen years. The teen is struggling to develop their own identity and to separate from their parents. Their parents want them to be independent but worry that they won’t be safe. The result is a push and pull that is very hard on everyone.
The best way through it is honest communication. It’s just possible that your parents have some legitimate concerns. You won’t know if you aren’t open to hearing what they have to say. It’s equally possible that this guy is a fine person for you to be with. They won’t know if they won’t listen to what you have to say.
I suggest you back up and show just how mature you are. Instead of arguing about the relationship, do your best to have a conversation with your parents about how you are all going to navigate the next few years together. You need to have some freedom to make your own decisions and to make your own mistakes. They need to know that you understand how to keep yourself safe. Do your best to stay calm and not to be defensive. Understand that their “disapproval” is most likely an attempt to keep you safe, not an unreasonable attempt to control your life.
Meanwhile, do everything you can to demonstrate to your folks that you are a responsible person who makes good decisions. Do well in school. Choose good friends who are good to each other. Do your responsibilities at home with a smile. You may well find out that your parents will start to relax if they see you maturing and taking responsibilities seriously.
I wish you well.