Let's make an analogy, let's say there's a 16 year old kid and his mom freaks out over the absolute smallest of things, just because he's not an amazing and perfect kid. Every time he does something that his mom doesn't like, his 8 year old sister breaks down into tears from the yelling. His mom is absolutely unreasonable, but if the kid continues to go out of his way to do things that he knows she won't like, he's an ass. He's an ass because he's causing his 8 year old sister to freak out just because he refuses to listen.
That's what the Sullivan-Kessel-Malkin dynamic is like here. Sullivan is the biggest aggressor because he's supposed to be the coach and is supposed to be able to mediate these kind of things, but Kessel is being a problem by intentionally not listening to him.