This in and of itself is not illegal, if the 14 year olds parents are agreeable to it. Despite not being illegal, it is inappropriate and creepy. On the other hand, if by dating you mean sex or sexual activity, then it is absolutely illegal.
Can you be 14 and date a 21 year old?
They should not date a 14 year old because of the risk of, among other things, statutory rape. The pictures are also potentially subject to criminal charges if they reveal any nudity.
Is a 15 year old dating a 21 year old illegal?
A number of state codes specify age ranges outside of which parties cannot consent to sex. Thus, sexual relations between a 15-year-old and an 18-year-old would be legal, while the same relationship between a 15-year-old and a 21-year old would not. Minimum age of victim.
Is it bad to date a minor?
Yes. Having sex with someone who is under the age of consent is a crime. In California, it is statutory rape. It is considered rape because it cannot be consensual.