They live in Perth Western Australia. They work together and it seems like a consensual relationship. I mean he would do anything for her and vice versa.

You have to check the age of consent in australia,. in the U.S. it is considered illegal.
Although if he is a school teacher then it should be brought to attention.

The age of consent for Australia is 16. Any adult who wishes to complain can have the man arrested, no matter how much she loves him and has entered the relationship willingly.

Also it can even be more serious if he is her boss.

It needs to be reported