I don't know why we have a search function; no one ever uses it.
Okay. Once more. For the 3,725,462th time, NO. There is NO law in ANY state that says at what ages you may DATE. That decision is left entirely in the hands of the parents. If the parents agree to let their 15 year old go to school events or movies or what-have-you with an 18 year old, the law will not stand in the way.
There ARE laws that say who may have sexual contact (which is NOT limited to intercourse.) The age of consent in Texas is 17. Tell the 18 year old to keep his hands to himself and his pants zipped, and we'll all be happy.
I swear I'm going to start charging for this question, it comes up so often.