It is difficult to give recommendations without knowing the full circumstances of the case. It is advisable to get a senior scholar, or cleric, to meet with your parents and discuss the issue with them.

You may have heard the hadith that says that if a believer comes to ask for the hand of a young woman, and he is rejected for no Islamic reason, 'fitnah will spread on the earth.'

Cultural and family issues require sensitivity though. Your parents, and his parents need to be helped to overcome their fears. I knew of an English woman who married into a family and her mother-in-law initially threatened suicide, but after some years, all the other families in their community were saying that they wished they had a daughter-in-law like that English woman.