I recommend Master Call Me Bai Susu to you! The male protagonist was the female protagonist's master. He was much older than the female protagonist. He watched the female protagonist grow up and gradually fell in love with her. He wore white clothes. Master had been very harsh to the female protagonist from the beginning, but the female protagonist had always been suspicious and curious about him. Later, she realized that Master had always cared about her, but she had never shown it. Back to the male protagonist's attire, he was often described in novels as wearing a white Daoist robe. I hope you like my recommendation.😗