Anger was not the only feeling running through Matthew, hate, loathing, rage, and pain. Pain from being betrayed by Jane and Finn, the two people he trusted most in the world, had gone behind his back and stabbed him.
He tried to figure out what had gone wrong, was it his fault? He was loyal to her, respecting all her wishes. She was the woman he was going to marry and spend his life with forever, yet it seemed like he didn't really know her.
Was it because he was not as charming as Finn? He knew he was not as expressive about his emotions, but he had a lot on his plate, and he had to be rigid and stern if he wanted people to follow him.