Oh my goodness... In New Hampshire it is illegal to walk with your shoes untied. The point being - common law "marriage" would require a 12 and 14 year old to live together outside of marriage and that just does not happen now a days so it is not a legal issue. In New Hampshire they don't prosecute or arrest the man with his shoe untied even though it is on the law books.
Lots of things are formally illegal, but not prosecuted...until someone wants to prosecute for some reason.
For example, it's illegal in Kansas for kids under 16 to have sex with each other. Everyone knows it's going on, but there aren't prosecutions for this.
Ah...but, when the Mayor of Salina catches his 15-year-old daughter having sex with the 15-year-old son of a sharecropper, the law suddenly has someone to prosecute. That's a hypothetical case, of course, but similar things have happened many times across this country.
That's why vague, "unenforced" laws need to be taken off the books. They're "unenforced" until it's convenient for someone to use them to enforce some other agenda.
Now, you may think, as does the DA mentioned in the article, that some pimply faced boy feeling up his girlfriend is a crime. I don't think that way. But, under this law, a prosecution could take place. I'd hope the jury would laugh the case out of court, but you never know.
Think back on your teen years. Did you do anything you could have been prosecuted for while you were a teenager?