Okay, so basically, I go to highschool with some friends I consider to be pretty good. At the very least, they're decent to me. They have a tendency to not get along well with eachother. I really hate the constant conflicts between them, but they continue to hang out with eachother. I can't separate them despite the fact that they seem to outright hate eachother, and only get along for brief periods of time.

One person in the group[we'll call her Allie (not her real name)] has a tendency to frequently hit another person[nicknamed Dan] in the group, sometimes over minor stuff or for no reason at all, like shaking a bag of chips to evenly coat them with seasoning. Basically, she straight up acts like she hates him, sometimes. 

Dan has a tendency to take or mess other people's with stuff without permission[I tried to leave the group after an incident where I had to pick up my stuff and was nearly late to class because he stole Allie's mechanical pencil[to eat the lead a second time that day], and I dropped my stuff, but I guilt tripped myself into going back to them], like food, a computer that someone is already using, etc.

The entire group seems to hate on a third guy for seemingly no reason, one incident that springs to mind is when Allie got mad at him for making jokes. They weren't about any serious topics like death or something like that, she literally just got mad because, in her words, "I hate jokes" [she would joke with us very frequently]. 

I'm scared to confront them about this, since they'll probably ignore me, or just say that i'm being stupid and whining for nothing. Am I the asshole if I would rather go be alone than be around them when they're together?

TL;DR- basically, I'm good friends with people. They treat me okay, but they act like they hate eachother sometimes.