She's one of your best friends in the entire world, and you hate to see her so upset, especially when you can't actually be there to hug her or hold her or refill her drinks. Stroke her blonde hair and tell her that it isn't her fault he broke up with her. Your heart still aches, and you see a post on the forums you're all a part of, and a bubble of rage just bursts inside you. You can't protect her, no, but you sure as fuck can defend her from the asshole that broke her heart. He's on the forums talking about partying with any old girl. How is that right?
So you do, you defend her because that's all you can do, even if you feel guilty for causing a scene. Even if you feel guilty that you can't do anything else while you're locked away in your little makeshift prison because she's one of your best friends, and you don't want to see her hurt. You do want to see him hurt.