<human>: Condense the text into a few key points

Okay, so my friend (16/m) is being essentially used as a pawn by a girl that he quite obviously used to like, and still has feelings for. Apparently, she caught on, and even though she is in a relationship with someone already, is constantly flirting with him, hugging him, stroking his arm, shit like that. However, it seems to me that she does this only for the purpose of using him. When she doesn't understand schoolwork, she comes whining to him. If she needs anything done and is just too lazy to, she tells him to do it, and he immediately agrees. I don't think I have ever seen him say no to anything she asks him to do, no matter how difficult a task. Another friend of mine [16/f] has already confronted him about this, and he blatantly refused to talk about it, writing it off as a nonexistent problem. He's the only one who doesn't see it. I just don't know what to tell him, if anything.
<bot>: My friend is being used by a girl who he has feelings for (though she is in a relationship with someone else), and he doesn't see it. How do I tell him?