Missy is 40 years old and has an 18 year-old, and would track down and BEAT THE FACE IN of a 39 year-old showing inappropriate interest in said 18 year-old.
Dude is playing with fire on SO many fronts, it's not even funny. Law aside (though not too far aside), he ought to be praying to every deity he can possibly name that the girl's Daddy doesn't show up with intent to perform a Bobbitectomy on him. Without anesthesia.
she can do whatever she wants when shes 18-untill then, id advise you to leave her alone before you get yourself in serious legal trouble.she is legally a child. you are an adult who should know better. find someone your own age.