I'm not trying to start anything (and I am normally not one to say anything), but this bothered me and seems kind of mean to pick out things you hated. Of course I don't know the girl or the situation, but to me, it seems as though she valued your opinion and wanted to impress you. I have plenty of friends who have a hard time picking out things or knowing what looks good on them, and they frequently ask me to help them pick things out. I love doing it, and I love making my friends or anyone else feel great about themselves.
Next, (and I'm not directing this at OP or LVLoveAffair this is more something I have heard from my own friends lately) but I just don't understand the "anger" behind someone "copying" the things we buy. This is flattery more than anything else. I understand it can be annoying if someone constantly does it, I guess? But come on. These people obviously look up to you and want to impress you when they "copy" the things you buy. I'm always happy to tell someone where I got something when they love it. Why would I keep that to myself? It just means I'm a trendsetter with good style haha, and I'm more than happy to share it. Now if they are rude about it and then show up with it the next day, that's a different story.
The biggest annoyance I agree about with everyone here is when people ask how much things cost. How nosy and rude!! It makes me so uncomfortable.