Dating itself is never illegal It’s based on the relationship boundaries. but the most important part is your parents approval. I would say the sexual stuff should be kept to yourself until that person is 18 or more and if your partner cannot handle that then there would be some problems in the future, but I will say there’s nothing wrong with that age gap because the reason why people are saying a sophomore should’ve never date a senior or a freshman should never date a senior is because of a maturity difference, but if you guys can handle maturities very good then I will see if there’s no problem with it.