I think there is a few things, which make a good portrait. Some of them are here, but only the secondary . Here I can see, that a very shy girl is standing beside presumably a man. She has closed eyes, very common thing with people not very comfortable with the situation. He is hiding his face altogether.Actually I can feel a negative tension between the people. That doesn't make a good portrait. There is nice choice of the background behind the heads and good work with DoF. But the white shirt is loosing detail, it is overexposed, makes one big blindly white spot right in the middle. In b&w photography white not necessarily has to be white, only it should look like white in reference to other values.