How can I prove to my dad it's not illegal? Can he not do anything once I turn 17?

New York says you're incapable of sexual consent till you're 17. Even if you and your boyfriend aren't having sex now, based on the facts & circumstances your boyfriend could be charged with endangering the welfare of a child. If your boyfriend has sex with you when you're still 16, he could be charged with sexual misconduct.

You could have your dad read Penal Law Article 130/which can be found at : http://ypdcrime.com/penal.law/article130.htm

You are wrong. There is the law, which you can look up on the internet and show him, and then there is reality. Where will you live? Who is going to support you? As long as you live at home, your parents hand down the law.

I don't think it's going to matter to your dad whether it's legal or not. And really, as long as you're living in your parents house it's them who make the law.

Who do you love more - your boyfriend or your father? If you love your father you ought to respect his wishes. I know it sounds cliche but your father knows men better than you ever will. I am sure he simply wants what is best for you. And if your boyfriend truly respects you then he will respect your father as well and seek his permission before trying to go against his wishes. As others have stated, while he may not be able to have your boyfriend arrested, so long as you are living at home under his roof he is the law.