Everyone has his own personality and interpersonal style. If he doesn't want to make friends with you, it may be because he thinks you don't have much in common in personality, hobbies and age, or he doesn't want to establish a friendly relationship with you at all. Perhaps the difference between age and gender is not the key factor, but mutual hobbies and social circles. Respect his thoughts and decisions, don't be friends with him, and don't take this matter too seriously. You can find other like-minded people to communicate and share.