Could my friend get in trouble?

Well a good girl friend of mine, who is 17 recently started having with her 13 year old boyfriend... which I think is not at all appropriate, but who am I to judge. Anyway, I was curious as to the legality of this issue. We live in Texas, and I know the legal age of consent is older than 13. Anyhow, his mom is very strict and I'm afraid that if she finds out my friend could get in trouble.