There are the ones that don´t want to fall in love. Pursay you have a lover already but is married to someone else? That was Namjoon right there. he really didn´t like this ´Rei´ girl. He wasn't fond of her either. They didn't like each other at first, but who can blame them right?But a business investment comes into place and they are forced to marry each other. 

The husband becomes abusive. But everything can change in the end. Apologies are told and hateful things are told.