Regarding Marriage Problem

Hello Sir, Mine sister is married to a guy in november 2017 and after that she was living with her in laws for sometime. Her husband is not taking care of her, he behaves like he didnt care. She lives for short time with him also but he went to office early in the morning and come very late night. She didnt call my sister .We tried to talk to him but he pretend to be very busy with his office and talk to us normally. But he told my sister that this is arrange marriage and without my consent so i dont want to live with you and dont interfere in each other lives. He acts like he still unmarried and didnt take any responsibility. My family is very tensed as we have spent large sum of money in marriage and my sister lives on stake. His family tried to convince him so much but he is tok resistant. His whole family is with my sister but he didnt sense his responsibility and didnt talk with her. My family treats him very good even after all these things. Please suggest me what to do as we dont want to break the marriage and just want that he becomes normal. We also have doubt that he may be have any affair outside. Please suggest me what to do without breaking the relationship. Or if we can file a case on this ground, and what will be the probable action in this case.