Marriage not registered now wife harassing to file dowry case

My doubt is that I have already finished my marriage as per religion with everybody's consent (Family). But my wife and I, both are working and are at different locations. So we have stayed together for twenty five days together out of six months of our marriage. I have no registration certificate of my marriage. My wife is still living with her brothers. Suddenly from few days I have seen a change in her behavior. She has started giving threats to me and my family on legal grounds. She says one complain I will make for dowry and everyone of you will be in jail.. Also want to inform that my wife left me, because she could not adjust with environment and food habits and that's why she abandon me and put false cases, since she wanted me to settle in Ernakulam but I denied it. I do remember the date, time and train number, by which she went with her parents from Pune, but I don't have ticket information. So is it enough to deny her maintenance? Thanks in advance.