oh dear lord.. yes you can date a 16 year old as long as her parents are okay with it. can you have sex with her legally? no. that's where you'll get into trouble. but simply dating is fine. 2 years is not a big deal.
I can see by your last question that 2 "happy birthday"s are in order.
Great answers. However, let me add.. some people said if you get the parents' permission it'll be ok. Not true. Anyone could 'turn on you' and turn you in. Step back. Turn around. Walk away. Don't look back.