What is the ruling on a girl refusing a religious and moral young man who proposed to her twice, due to differing customs and traditions, knowing that the problem of their differing customs can be resolved?

If a young man proposing to a girl is of good character and religious commitment, then the girl should agree to marry him. This is in line with what Islamic law encourages in the hadith: "If someone whose religious commitment and character you approve of proposes to you, then marry him. If you do not do so, there will be tribulation on earth and widespread corruption." The fact that his environment is unsuitable is not a legitimate impediment according to Islamic law. If the girl is unable to convince him, then the young man should look for someone else and supplicate frequently.