*But she did not have an inappropriate relationship with him, did she?
Much as you and some others may wish to read into it, their relationship did not begin until afterwards.*
He fancied her & pursued her when he was 15 & she was his teacher.
His parents were concerned enough to send him away to a different school, but they stayed in touch & got together properly a couple of years later.
As his teacher she should have poured cold water onto any infatuation from her pupils.
He was a pupil of hers, she was in a position of power wrt him at that time.
The onus was on her to not countenance it, let alone encourage it by 'staying in touch'.
The term 'precocious' has been used about Macron in terms of both his abilities, and the fact that it was he who pursued a woman his senior, not the other way round.
The term 'precocious' is often used about non-adults that 'pursue their seniors'.
Lolita was 'precocious'.
As a person in a position of power, I would expect a teacher (male or female) to be 'able to resist the advances of their precocious pupils'.