My friend's wife is a vegetarian but he is a non-vegetarian. Now she wants him to convert and he does not like it. What should he do?

food, clothing, friends, choice of entertainment etc are based on individual decision. her nagging may force him to eat vegetarian but he will eat out non veg food in restaurants. so what's the use of force? it will only create a bad image in his mind for his wife and work badly for his self esteem