Legal Question in Criminal Law in Texas

Possibly, it depends what they do when they "go out," and whether or not there is more than three years age difference.

If the 17 year-old is more than 3 whole years (even by one day) older than the 14 year-old and they have any sort of sexual contact, then yes, this is a felony in the State of Texas, carrying 2 to 20 years in prison. It technically is a crime even if the 17 year old is less than 3 whole years since the 14 year old is deemed to be unable to consent, but as the other lawyer pointed out, there is a defense in the Penal Code for someone within the 3 year range, so long as that person is not required to register as a sex offender.