At 13 she knew what she was doing, people need to stop thinking that teens don't know what the hell they are doing. Yes its bad that the guy took advantage of her, but who's to say she didn't use the guy to get cool stuff. She got a phone from him, and the only reason it caught on was because the mother (whom works 3 jobs) found out she had a phone.
So chances are the girl used the guy to get stuff because she don't get much as her mom works 3 jobs and probably makes barely enough to support herself and her kid. Since there was no mention of a father and the fact she is working 3 jobs means that the girl is most likely from a broken home(meaning its not all lollipop's and rainbows).
But the way things are in todays society the dude will have one of two things happen, either made an example of (most likely) or get like 10 years probation. As for the girl, I believe she knew what she was doing, she got stuff from him and in return he got sex.