NAH. You should tell her that you are worried because of the things you heard. But don't be harsh on her. Even if she chooses him over your friendship now, she will come back once she is done with that guy. He sounds like an idiot. But the real idiot here again is love. You can't blame her right now for being blind. Relationships that start this quickly at such a young age often don't last long. Once she notices how much of a mismatch this dude is, she'll most likely fall out of love pretty quickly. It might end up hurting but no one can protect us from getting hurt in love. It's a process we all go through at some point in our lives, and we always grow from it. Just do what you think is the right thing as a true friend.