Is it illegal for a 28 yr old to date a 17 yr old in the state of Texas?

Why would you want to?

Depends on what goes on during the date.

Dating is not illegal, but physical activity is, yes. Date someone closer to your age if you can..

Dating is one thing, sex is another as it may be legal for a 17 year old to date an adult, but your parents have the final say in the matter.

The age of consent (having sex) is 17,
Section 22.011 (a) (2) of the Texas Penal Code provides that a person who has sexual relations with a child younger than 17 years of age is guilty of Sexual Assault. Under this section of the Penal Code, "sexual relations" may include conventional sexual intercourse, oral sex, anal sex and/or oral-anal sex.

I would certainly not go against her parents. Legal, or illegal by law.