It is illegal for an adult (someone 18 or older) to have sex with a minor (someone younger than 17), even if the sex is consensual. Those who break the law have committed statutory rape (classified as sexual assault in Texas).

What is the oldest a 14 year old can date in Texas?

17: The age of consent in Texas is 17. The minimum age is 14 with an age differential of 3 years; thus, those who are at least 14 years of age can legally have sex with those less than 3 years older.