Can a 25 year old man date a 16 year old girl in the state of South Carolina?

The age of consent in South Carolina is 16, so the answer is yes.

This is from Wikipedia:SECTION 16-3-651. Criminal sexual conduct: definitions...(h) "Sexual battery" means sexual intercourse, cunnilingus, fellatio, anal intercourse, or any intrusion, however slight, of any part of a person's body or of any object into the genital or anal openings of another person's body, except when such intrusion is accomplished for medically recognized treatment or diagnostic purposes.SECTION 16-3-655. Criminal sexual conduct with a minor; aggravating and mitigating circumstances; penalties; repeat offenders. (B) A person is guilty of criminal sexual conduct with a minor in the second degree if:...(2) the actor engages in sexual battery with a victim who is at least fourteen years of age but who is less than sixteen years of age and the actor is in a position of familial, custodial, or official authority to coerce the victim to submit or is older than the victim. However, a person may not be convicted of a violation of the provisions of this item if he is eighteen years of age or less when he engages in illicit but consensual sexual conduct with another person who is at least fourteen years of age. In addition, mistake of age may be used as a defense.SECTION 16-15-140. Committing or attempting lewd act upon child under sixteen. It is unlawful for a person over the age of fourteen years to willfully and lewdly commit or attempt a lewd or lascivious act upon or with the body, or its parts, of a child under the age of sixteen years, with the intent of arousing, appealing to, or gratifying the lust or passions or sexual desires of the person or of the child.

Completely separate answer...

Are you aware that you could be killed for that if the wrong crowd of people found out? They don't take too kindly to that around your parts.