Please note that this answer does not create an attorney-client privilege.
It is not against the law in Texas for two minors to have sexual relations. The three-year rule, the so-called "Romeo and Juliet statute", applies in a case in which one party is a minor and the paramour is an adult. As long as there is less than a three year difference in ages, it does not quality as statutory rape.
I must warn you, however, that regardless of the age of the participants, consent is always an issue. It doesn't take an act of violence or the threat of violence to make the act non-consensual. Any kind of pressure placed on the other party could be considered coercion.
I agree with Mr. Kennedy. If a 17 year old and a 15 year old have consensual sex, there should not be a criminal charge to worry about. If the act is not consensual, then there would likely be some criminal liability.