@Dancerdove,
Look, this is really an easy answer. When I was 17, a young lady caught my eye. She was sweet and very easy on the eyes. I decided to ask her out. She told me she would have to ask her parents, with which I had no problem. Then her mom called me to let me know her daughter was only 13 years old and basically questioned my sanity with wanting to date a 13 yr. old. Now, I swear she looked 15 or 16 at the time. Well developed, if you know what I mean. And she never told me she was only 13. Anyway, once I knew she was so young, I quickly backed away. She and I remain friends to this day (35+ years later) and can still laugh about it. I sometimes wonder what kind of problems would have ensued had she not told her parents about my interest in her.
The point is, if you don't think you can tell your parents about it, then it probably is not a good thing. That is a pretty good rule to follow with just about anything in life. Just tell the guy you are too young to date someone his age and just want to be friends. In 4 years, at 18 and 21, the age difference will not mean as much and if you are both available you might revisit the dating thing. (My wife was 16 and I was 20 when we began "dating," which for the first 10 months or so consisted of only getting together at her house, with mom and dad present, to hang out. They got to know me and were comfortable with the age difference. Tam and I were patient about it because we knew the difference was substantial at our ages and of course I did not want any charges brought against me by her parents. lol So be patient. You have a lot of life to live.)