I could so relate to her lack of emotional display, that really hit close to home, I am fine at expressing myself online and can be angry but I'm not so great at expressing much in real life. And when bad things happen I just go into cold practical mode like that. It was worse when I was younger too.
But yeah, there must have been something up with him, that's really bad / sad for her, he was being very ignorant of how to treat her and being with another woman is the worst. Of course those of us who don't react often have people do things to us to provoke a response but if it gets bad, the relationship just usually ends whether it be friends, lovers or family because the person that doesn't display was feeling bad all along and has already had too much when they do react and that's usually just to leave or blow up and leave because it was the final straw and the other person was not observant enough to know better.