There are no laws about dating. There are laws about sexual contact. Given that there is no reason for a 19 year old to go out with a 15 year old other than illegal activities, it would be very wrong.
Of course it's legal. She's 18, making her a legal adult, same with the boy.
no
No..but yes
no. no.
Yes, it is legal.
sure! why not?! you can date who ever you want!
There are no laws against it.
yes.
yes it is.
Date? Yes as long as legal guardians don't object. Have sex with? No. You are jail bait, or "Under the legal limit"
Yes it is.
No, but do it anyways.