Welcome to Fluther.
This is a difficult question to answer. On the one hand I have a granddaughter who is just a bit younger than you are, and I know that in her case because of her immaturity and, frankly, ignorance of much of the world, I understand why laws are written to address the legal fiction that people younger than you are are “incapable” of consent. That is, despite my granddaughter understanding the basic “facts of life”, she has absolutely no idea of how the world can and usually does operate outside of the walls of her house, her school, and her head. So I hope like hell that she’s not having sex, despite how boy-crazy I also know her to be. Her parents have a tough road ahead of them for the next few years, I’m afraid.
But here you are, and let’s assume that you really are (and were at the time) more aware of the realities of life than my granddaughter. The state doesn’t evaluate people on a case-by-case basis in terms of setting the age of majority, the drinking age, the age when teens can legally drive, and so forth. They do the best they can to judge entire populations and say “Yeah, right about this age might be… okay. And heaven help us.” So, the short answer to your question is that it’s unlikely that you can get the charges dismissed. The law is the law and these age limits are written clearly into it.
Let’s say that you’re an exceptional teen who has been capable for a lot longer than most of making such decisions about yourself and your conduct, and that you have been and could have been responsible for all of your decisions. The state doesn’t care, in the case of your boyfriend. He (apparently – we’ll get to that) crossed a line that he shouldn’t have because you had not reached the magic “age of consent”.
Well, I’m not going to suggest that you perjure yourself or lie about anything that has happened – that would not demonstrate maturity on your part! But if the state can’t prove that sexual relations ever occurred, then they don’t have a case, do they? So, that being the case, what do the prosecutors know – that they can prove? Has your boyfriend made any damning admissions? Are there photos, video or written accounts of sexual encounters?
You probably can’t refuse to cooperate or testify, or refuse to answer some questions during pre-trial investigation or at the trial itself; the prosecutor then would request (and probably receive) permission from the judge to treat you as a hostile witness, and then the questioning would be even more intrusive than it is bound to be anyway. The prosecutor has a fine line to walk there, because if you’re supposedly a victim, yet he has to treat you as hostile to his case, then that won’t look good in front of a jury. But prosecutors can finesse that, so don’t rely on sympathy from the jury.
So that’s my first advice: Don’t lie; don’t perjure yourself – the penalties to you for that could be almost as severe as what he’s facing. But do realize that their entire case may hinge on you and what you admit to. If there’s no other evidence of a sexual relationship than what he and you say, then… there’s no case. So don’t feel that you need to assist the prosecutor, either.
The best way that you can assist your boyfriend, I think – and I’m not an attorney so nothing here is legal advice – is to cooperate with his attorney in his defense; to not “assist” the prosecutor in making his case (it may be worthwhile to enlist an attorney on your side to determine at what point you may – legally – refuse to answer investigators’ questions); and to speak clearly, plainly and forcefully in your own behalf, which will demonstrate to all involved that you are not a timid, immature victim, but a capable and mature young woman.
Good luck to you all.