In Florida, a 16 or 17 y/o can, legally / lawfully, consent to sexual relations with someone who is 23 or younger.
If you are younger than 16 then your consent, no matter how heartfelt, is legally insufficient and will not be a factor in an ensuing criminal prosecution. Similarly, if you are able to consent (if you are 16 or 17) but you have sexual relations with someone who is 24 or older, then your consent is similarly legally insufficient and will not be a factor in an ensuing criminal prosecution.
That said (shy of falsely imprisoning or securing chastity equipment), while family cannot stop a minor who is legally capable of giving consent from doing so, the legal guardian of a minor can seek protection from the Court on the minor's behalf and against the minor's will in the form of a restraining order / injunction for protection.
If the Court believes that it is in the minor's best interests to issue the order of protection then it can lawfully preclude any contact, direct or indirect, between the minor and the up to 23 y/o sexual partner. Any violation of such a Court Order will result in immediate incarceration and an independent criminal prosecution.
Whether or not a Judge would issue such a stay away order (a permanent one anyhow) is subject to the minor being able to speak her/his mind, and, naturally such a course of action, if pursued, is likely to drive a significant wedge into any familial relationship.
That's the law. Its black and white. No exceptions. No excuses. No wiggle room. If either the minor is under 16 or the adult is over 23 the its a 100% "NO", and if both parties consent and fall within this age range then, for many reasons, it remains a delicate situation.
I hope that I have been helpful in answering your question.
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Her mom can get an injunction against you. If you violate that injunction, by even just sending a text message or an email, you could be convicted of a misdemeanor. While it is not against the law to have sex, the parents can convince the child that you raped her, that she did not consent, and if that happens, you will be branded for life and might even spend time in prison. I think it is best for you to become completely trustworthy and absolutely abstain if you want to be involved with this girl, at least until she is 18 when she can make her own decisions.
R. Jason de Groot, Esq. We do not have an attorney-client relationship. I am not your lawyer. The statements I make do not constitute legal advice. Any statements made by me are based upon the limited facts you have presented, and under the premise that you will consult with a local attorney. This is not an attempt to solicit business. This disclaimer is in addition to any disclaimers that this website has made. I am only licensed in Florida.