I was born in a traditional family, but I fell in love with a man fifteen years older than me. How can I convince my parents?

Always tell them about your relationship with your boyfriend, such as what he said to you and what he did that moved you. Remember to be practical, such as how he respects his parents. How can he comfort you when you are sad and so on. And no matter how dissatisfied your parents are with him, it's just their own unilateral thoughts. If you are not satisfied with this person and you can't understand until you meet him, then arrange for your boyfriend to visit your home and let him show more in front of your parents. I think your parents are more traditional, but it doesn't mean that they are opposed only because of their age, so you should know more about your boyfriend.