Navigating Hurtful Friend Group Dynamics

I need everyone's assistance immediately 😁 So basically um. Friend group of three. Friend 1 does something hurtful, doesn't matter what. Friend 2 resents friend 1, but decides not to tell them how they (friend 2) feel because they're drifting apart anyways and it's not that big a deal to them. So. I feel bad in the group, because friend 1 thinks everything is fine when it isn't fine and friend 2 isn't communicating what's true. The way friend 1 acts like they're ok with friend 2 feels wrong in my opinion, and although I understand the way friend 1 feels, it makes me kinda angry at them. It isn't my problem, it's theirs. I don't know why it affects me the way it does. I KNOW their feelings are valid, I KNOW my feelings are valid. I'm just really not sure what to do now. What to do with this anger. Should I just let it pass over? /gen