Been in the same situation and as per my experience, this type of people always want to show the world that he is so nice and sweet. Basically want to create good image in others eyes to gain respect. I can say they have some kind of inferiority complex. He knew that he is not good but he tries to give fake impression to others, that he is so sweet and nice.
RE: Why does my husband act and talk nicer to everyone else but me? 为什么我的丈夫对别人都比对我好？