Absolutely f*cking illegal.
I personally find it okay for a 13 and 15, and 14 and 16.. but 13 and 16? You got to be F*CKING kidding me.
Friend: Yo I datin a girl.
Friend 2: How old is she?
Friend: She's 13!
Friend 2: Aren't you 16? THATS A CASE MY GUY
Friend: Sh*t, not my fault shes so hot
So it's illegal for a 13 and 16 year old to date.