It's certainly true that some people have ridiculously broad definitions of rape. However, if this only fit one of the more questionable definitions, I doubt the guy would have admitted to raping her. And I don't think the girl would have been as angry and traumatized as she seems to have been if it was just statutory rape.
There are such things as plea bargains and his lawyer very well may have known the sentence would be what it was in convincing his client to admit to the rape charge.
As for the 14-year-old, can you not imagine a situation where she has gotten in trouble with her parents for her behavior and the way to avoid that is to turn on he "boyfriend." It also would not be the first time a 14-year-old that you and I would consider very complicit in the act asserted rape.
Again, we are forced into this speculation by a lazy job of reporting or a reporter that did not want us to know the circumstances.