there is a case right here in Ga right now where the guy was like 17 or 18 and had consentual sex with a girl. not sure of her age but I think I heard 15. anyway he has spent the last 3 yrs in jail. mind you the sex was consentual. both wanted it. now they are trying to get him released.
I for one would not allow my 15 yr old daughter to date a 20 yr old. like direction said I would question why a man wanted to date a 15 yr old. just my opinion.