if a 40 year old dates a 15 year old..and a 21 year old dates a 15 year old. it really dont matter cause her dad would probably kill you both. just another view from a father with a 17 year old daughter. id find out if he has a gun collection before going any further with this. and has he been in jail resently for assault. goin to jail could be the least of your worries.my advice to you would be find someone your own age.