depends on a lot of things. Like depends on if your parents are against it, take for example if you are the 16 year old and the 19 year old and you have sex and your parents find out even if they were okay with you two going out in the beginning they could press charges. I would check out the laws in your state. And if you were the 19 year old, it wouldn't be to good if something like that happened.
In most places, the age of consent is 16, so you're pretty safe, but it's good to make sure.
Otherwise, there's nothing "wrong" about a younger guy dating an older girl. If there is abuse involved, then it's wrong, but with only a 3 year difference, I seriously doubt it. It's uncomon for girls to date younger guys, but it's just because the GENERAL girl is supposed to mature faster than the GENERAL boy. However, it's different for each individual. It may be hard to make the relationship work, but that's up to you. I have a friend who dated a 19 year old girl when he was 16 and the relationship lasted several years.
like everyone else has said , it all depends. three years isnt much of a difference, if it was any more than that, it could be a problem. but, anyhow, if you guys are into each other and like each other enough, you can make it work. the age thing might be something that bothers your friends or parents, but if you prove to them that you guys can be mature about it and look past the age difference, i'm sure they'll learn to look past it too. i'm 18 and was a senior just this past year and i dated a guy for awhile who was 15 and a sophmore. but we never really saw the age thing as an issue and we had a great time while we were together. so, if you think they are worth it, then go for it and good luck!
when i was 17, about to turn 18 i dated a 13 year old guy who had the deepest crush on me, he was my brother's best friend. We only dated for about 2 months and both our parents didn't really approve of the relationship and we broke up. It might sound kinda of silly but we did love eachother dispite the age difference. We didn't really do anything sexual, just kissed once or twice. He didn't really look his age which fooled alot of people lol. His parents didn't really know me and they forced him to dump me cause they thought i was too old. Like his ex girl friend which i know was 4 years older then him and they liked her and i was also 4 years older till i turned 18, after we broke up. My parents only disapproved cause he was trouble but i brought out the best in him when we were together. I don't really think age matter as long as thier's not anything bad like sexual force or rape. As long as both like eachother it's ok. AGe is only a number lol.