I don’t know. I do know is many states (TX used to be one of them), it would be considered statutory rape if an 18-year old male was having sex with anyone under the age of 18. TX has changed the law a little to allow for high school romances so now an 18-year old can have sex with a minor ONLY IF the minor is younger by two years or less. If the minor is 2 years and 1 day younger than the 18-year old, the 18-year old is guilty of statutory rape again.
Also, the TX law doesn’t not specify gender so it doesn’t matter if it is a gay relationship, whether the adult is a male or female, or whether the minor is a male or female. I can’t speak for other states’ laws though.