Over here in the UK 16 is the age of consent, so there probably wouldn't be more effect on him, apart from bragging rights with his pals.

The teacher however could be arrested because of abuse of the trust and ostracised by her professional body.

There are often relationships like this that only come to light in later years. A friend of my daughter married her former teacher at 18 when she was at University, and they kept it hidden as he and she moved districts, so nobody ever sussed it where they moved to.