Damn. It's absolutely NO!
It takes a man a lot of immoral to that kind of thing. I tell you, love is not there. That kind of man is absolutely full of evil. Everyone knows the moment he courted the girl, he should treat her right.
One thing I completely assure is that there is no percentage of it being normal for a guy to slap a lady in a relationship. It is completely absurd. Relationships are made to be growing and love is all about accepting and giving. What the girls need are loving arms and gentle kisses to show how much we love them. They are soft hearted, easily fainted, and most especially very emotional.
Emotions play a big role into our lady partners. Slapping? - Totally a red flag and I advise you, to leave. Leave him.